I have a very large but stable load order but I have occasionly run into this same problem of crashing when saving. The best workaround I've come up with is to load up an earlier save and then leave the cell I am currently in (enter a building or dungeon, or run until the cell changes) and then save the game. This has worked every time for me for the 3 times this has happened to me, which were:
1) Inside the Kvatch Oblivion Gate outside the Sigil Tower. Loading an earlier save, killing all the daedra, then entering the tower and killing the bad guys on the ground floor then saving succesfully
2) Outside the Pale Pass during the Beyond the Vale quest. Loading an earlier save and entering the Pale Pass before saving allowed me to save successfully
3) Inside the Leyawin Oblivion Gate (the one required for the Allies of Bruma quest), inside the Sigil Tower. Loading outside the Tower and entering again was enough to save successfully
I find it curious that the 3 times it happened to me were in Vanilla quest locations but I suppose it could be coincidence. I have played for nearly 250 hours on this character so this is a very rare occurence and noone else has reported having issues at these three locations.
If you are running an autosave mod(kuerrtree's or Streamline) I would disable this until you have left the problematic cell and managed to save successfully. You can then reactivate it and go about your business
My savegame is 12MB in size so the size of your savegame is not an issue. I would second the reccomendation of Wrye Bash because it can also clean your saves by removing bloat (another potential cause of crashing in general). However it can't fix saves that have been corrupted in this way. And if you ultimately want a load order similar to mine then Wrye Bash is essential. Here's my load order to give you an idea:
Spoiler Active Mod Files:00 Oblivion.esm01 ScreenEffects.esm02 All Natural Base.esm [Version 1.0]03 Francesco's Leveled Creatures-Items Mod.esm [Version 4.5bSI]04 Francesco's Optional New Items Add-On.esm [Version 4.5bSI]05 Cobl Main.esm [Version 1.73]06 Oscuro's_Oblivion_Overhaul.esm [Version 1.34]07 Mart's Monster Mod.esm [Version 3.7b3p3]08 Enhanced Daedric Invasion.esm09 TamrielTravellers.esm [Version 1.39c]0A FCOM_Convergence.esm [Version 0.9.9MB3]0B Armamentarium.esm [Version 1.35]0C Artifacts.esm [Version 1.1]0D Open Cities Resources.esm [Version 3.5.5]0E bookplacing.esm [Version 1]0F Progress.esm [Version 2.2]** Cobl Races TNR.esp [Version 1.53]** Cobl Races TNR SI.esp [Version 1.53]10 Unofficial Oblivion Patch.esp [Version 3.3.2]11 DLCShiveringIsles.esp12 Unofficial Shivering Isles Patch.esp [Version 1.4.0]13 SM Plugin Refurbish - SI.esp [Version 1.30]** Oblivion Vwalk UOS.esp** DLCShiveringIsles Vwalk UOS.esp** DLCShiveringIsles Vwalk DG_DS UOS.esp14 Francesco's Optional Chance of Stronger Bosses.esp15 Francesco's Optional Chance of Stronger Enemies.esp16 Francesco's Optional Chance of More Enemies.esp17 Francesco's Optional Leveled Guards.esp++ FCOM_Francescos.esp [Version 0.9.9]++ FCOM_FrancescosItemsAddOn.esp [Version 0.9.9]18 FCOM_FrancescosNamedBosses.esp [Version 0.9.9]19 Atmospheric Loading Screens - Random Quotes.esp1A NaturalHabitat.esp1B All Natural.esp [Version 1.0]1C All Natural - SI.esp [Version 1.0]1D NaturalWater.esp++ ln.esp++ Symphony of Violence.esp1E AmbientTownSounds.esp1F MIS Low Wind.esp20 MIS New Sounds Optional Part.esp21 Atmospheric Oblivion.esp22 PCSoundRhett.esp [Version 2.6]++ Drum_Fix.esp23 Storms & Sound.esp24 Rainbows.esp25 All Natural - Real Lights.esp [Version 1.0]26 WindowLightingSystem.esp27 AliveWaters_nofish.esp** Book Jackets Oblivion - BP.esp28 Chapel Tithe.esp++ Cyrodilic Brandy.esp29 Days&Months.esp++ Item interchange - Extraction.esp [Version 0.78]2A Q - More and Moldy Ingredients v1.1.esp2B SoT_Holiday.esp2C Enhanced Economy.esp [Version 5.0.2]2D FF_Real_Thirst.esp2E Choices and Consequences.esp [Version 2.02]2F kuerteeIgnoringTheMainQuestHasConsequences.esp30 Display Stats.esp [Version 1.3]31 DropLitTorchOBSE.esp [Version 2.4]32 Duke Patricks - Follow That Actor.esp33 Duke Patricks - Friendship Ring For Companion Detection.esp [Version 1.8]34 FormID Finder4.esp35 Get Wet - just droplets.esp36 kuerteeAutoSaveAndTime.esp37 kuerteeCleanUp.esp38 kuerteeSittableRocks.esp39 Musical Immersion 1.0.esp3A P1DmenuEscape.esp3B ScreenControls.esp3C Streamline 3.1.esp3D Map Marker Overhaul.esp [Version 3.7.1]3E Map Marker Overhaul - SI additions.esp [Version 3.5]3F Enhanced Hotkeys.esp [Version 1.4]40 DLCHorseArmor.esp41 DLCHorseArmor - Unofficial Patch.esp [Version 1.0.6]42 SM Plugin Refurbish - HorseArmor.esp [Version 1.11]43 DLCOrrery.esp44 DLCOrrery - Unofficial Patch.esp [Version 1.0.4]** DLCOrrery Vwalk.esp45 SM Plugin Refurbish - Orrery.esp [Version 1.11]46 DLCVileLair.esp47 DLCVileLair - Unofficial Patch.esp [Version 1.0.6]++ SM Plugin Refurbish - VileLair.esp [Version 1.21]48 DLCMehrunesRazor.esp49 DLCMehrunesRazor - Unofficial Patch.esp [Version 1.0.5]** DLCMehrunesRazor Vwalk UOP.esp4A SM Plugin Refurbish - MehrunesRazor.esp [Version 1.30]4B DLCSpellTomes.esp++ DLCSpellTomes - Unofficial Patch.esp [Version 1.0.1]++ MaleBodyReplacerV4.esp++ MaleBodyReplacerV5Beta.esp4C ClassyClothingCompendium.esp++ CM_Better Wine.esp4D DLCThievesDen.esp4E DLCThievesDen - Unofficial Patch.esp [Version 1.0.7]4F DLCThievesDen - Unofficial Patch - SSSB.esp [Version 1.0.4]** DLCThievesDen Vwalk UOP.esp50 SM Plugin Refurbish - ThievesDen.esp [Version 1.30]51 Cobl Glue.esp [Version 1.73]52 Cobl Si.esp [Version 1.63]53 FF_Real_Thirst, Cobl.esp54 Bob's Armory Oblivion.esp55 FCOM_BobsArmory.esp [Version 0.9.9]56 Oblivion WarCry EV.esp [Version 1.09]57 FCOM_WarCry.esp [Version 0.9.9MB5]58 Oscuro's_Oblivion_Overhaul.esp [Version 1.34]59 OCC-OOO-Patch.esp [Version 2.4]** Oscuro's_Oblivion_Overhaul Vwalk.esp** OMOBS.esp [Version 1.0]** OMOBS_SI.esp [Version 1.0]5A Choices and Consequences - OOO.esp [Version 2.0]++ ArmamentariumLLVendors.esp [Version 1.35]5B ArmamentariumArtifacts.esp [Version 1.35]5C OOO 1.32-Cobl.esp [Version 1.72]5D FCOM_Convergence.esp [Version 0.9.9Mb3]++ FCOM_EntropicOrderRebalance.esp [Version 0.9.9beta2]5E FCOM_RealSwords.esp [Version 0.9.9]5F FCOM_DurabilityAndDamage.esp [Version 0.9.9]60 Mart's Monster Mod - More Wilderness Life.esp [Version 3.7b3p3]++ FCOM_SaferRoads.esp [Version 0.9.9]++ FCOM_LessRats.esp [Version 0.9.9]++ FCOM_LessReaversInGates.esp [Version 0.9.9]61 Mart's Monster Mod - Extra Wounding.esp [Version 3.7b3p3]++ Mart's Monster Mod - Looting NPCs & Creatures.esp [Version 3.7b3p3]++ Mart's Monster Mod - Less Reavers.esp [Version 3.7b3p3]62 Mart's Monster Mod - Safer Quest Locations.esp [Version 3.7b3p3]63 Mart's Monster Mod - Dungeons of MMM.esp [Version 3.7b3p3]64 Mart's Monster Mod - Gems & Gem Dust.esp [Version 3.7b3p3]65 Mart's Monster Mod - Hunting & Crafting.esp [Version 3.7b3p3]66 Mart's Monster Mod - Farm Animals.esp [Version 3.7b3p3]67 Mart's Monster Mod - Diverse WaterLife.esp [Version 3.7b3p3f]++ Mart's Monster Mod - Slof Horses Complete.esp [Version 3.7b3p3]++ Mart's Monster Mod - Diverse Runeskulls Loot G&GD.esp [Version 3.7b3p3]++ TamrielTravellerAdvscript.esp [Version 1.39c]68 TamrielTravellers4OOO.esp [Version 1.39c]** TamrielTravellers4OOO Vwalk.esp++ TamrielTravellersItemsnpc.esp [Version 1.39c]69 TamrielTravellersItemsCobl.esp [Version 1.39c]6A ShiveringIsleTravellers.esp [Version 1.39c]** ShiveringIsleTravellers Vwalk.esp++ ShiveringIsleTravellersFriendlyFactions.esp [Version 1.39c]++ FCOM_TamrielTravelers.esp [Version 0.9.9]++ FCOM_DiverseGuardUnity.esp [Version 0.9.9]++ FCOM_BobsGuardUnity.esp [Version 0.9.9]++ FCOM_HungersUnitySI.esp [Version 0.9.9]** FCOM_FriendlierFactions.esp [Version 0.9.9]6B FCOM_MoreRandomSpawns.esp [Version 0.9.9]6C FCOM_MoreRandomItems.esp [Version 0.9.9]++ Mart's Monster Mod - Shivering Isles.esp [Version 3.7b3p3]++ ArmamentariumLL4OOO.esp [Version 2.01]++ ArmamentariumLLMagicOOO.esp [Version 1.35]++ FineWeapons for OOO.esp** Fransfemale.esp** RustyItems for OOO.esp++ MMM-Cobl.esp [Version 1.73]** EVE_StockEquipmentReplacer4FCOM.esp6D EM_CompInnsleeping.esp [Version 0.9]6E Artifacts.esp [Version 1.1]++ Artifacts - ArmaCompleteAddon.esp [Version 1.0]6F Kragenir's Death Quest.esp** Kragenir's Death Quest Vwalk.esp70 KDQ - Rural Line Additions.esp71 LetThePeopleDrink.esp [Version 2.5]72 KragenirsDeathQuest-LetThePeopleDrink patch.esp73 The Ayleid Steps.esp [Version 3.4]** The Ayleid Steps Vwalk.esp74 Cyrodiil Travel Services.esp [Version 2.0.5]** Cyrodiil Travel Services Vwalk.esp75 za_bankmod.esp76 DLCBattlehornCastle.esp77 DLCBattlehornCastle - Unofficial Patch.esp [Version 1.0.5]78 SM Plugin Refurbish - Battlehorn.esp [Version 1.30]79 DLCFrostcrag.esp7A DLCFrostcrag - Unofficial Patch.esp [Version 1.0.5]7B OCOD+FrostcragSpire Patch.esp7C SM Plugin Refurbish - FrostCrag.esp [Version 1.2]** DLCFrostcrag Vwalk.esp7D Knights.esp7E Knights - Unofficial Patch.esp [Version 1.1]** Knights Vwalk UOP.esp** EVE_KnightsoftheNine.esp++ SM Plugin Refurbish - Knights.esp [Version 1.06]7F Choices and Consequences - SM Plugin Refurbish - Orrery.esp [Version 2.0]80 OCC-KOTN-Patch.esp [Version 3.0]81 The Lost Spires.esp82 OCC-Lost Spires-Patch.esp [Version 2.1]** The Lost Spires Vwalk.esp++ FCOM_Knights.esp [Version 0.9.9Mb3]83 Enhanced Daedric Invasion.esp++ FCOM_EnhancedDaedricInvasion.esp [Version 0.9.9]84 ElsweyrAnequina.esp++ ElsweyrAnequina - Races HGEC-Robert.esp [Version 1.1]** ElsweyrAnequina Vwalk.esp85 Tales from Elsweyr Anequina.esp86 road+bridges.esp [Version 4.5.8]87 Feldscar.esp [Version 1.0.5]** Feldscar Vwalk.esp88 Vergayun.esp [Version 1.0.5]** Vergayun Vwalk.esp89 Faregyl.esp [Version 1.0.10]8A Faregyl+Anequina Patch.esp** Faregyl Vwalk.esp8B Molapi.esp [Version 1.0]8C PTMudwater.esp8D xuldarkforest.esp [Version 1.0.5]8E LostSpires-DarkForest patch.esp8F xulStendarrValley.esp [Version 1.2.2]90 xulTheHeath.esp91 MMMMWL-TheHeath patch.esp92 XulEntiusGorge.esp93 xulFallenleafEverglade.esp [Version 1.3.1]94 LostSpires-Everglade patch.esp [Version 1.2]95 Anequina-Fallenleaf-Patch.esp96 xulColovianHighlands_EV.esp [Version 1.2.1]97 xulChorrolHinterland.esp [Version 1.2.2]** xulChorrolHinterland Vwalk.esp98 xulBeachesOfCyrodiilLostCoast.esp [Version 1.6.4]99 KragenirsDeathQuest-LostCoast patch.esp9A xulBravilBarrowfields.esp [Version 1.3.2]** xulBravilBarrowfields Vwalk.esp9B xulLushWoodlands.esp [Version 1.3.1]9C xulAncientYews.esp [Version 1.4.3]9D xulAncientRedwoods.esp [Version 1.6]9E xulCloudtopMountains.esp [Version 1.0.3]9F KragenirsDeathQuest-CloudtopMountains patch.espA0 xulArriusCreek.esp [Version 1.1.3]A1 xulPatch_AY_AC.esp [Version 1.1]A2 xulRollingHills_EV_withoutWheat.esp [Version 1.3.2]A3 MMMMWL-RollingHills patch.espA4 KragenirsDeathQuest-RollingHills patch.espA5 xulPantherRiver.espA6 xulRiverEthe.esp [Version 1.0.2]A7 xulBrenaRiverRavine.esp [Version 1.1]** xulBrenaRiverRavine Vwalk.espA8 xulImperialIsle.esp [Version 1.6.6]** xulImperialIsle Vwalk.espA9 xulBlackwoodForest.esp [Version 1.1.0]AA xulCheydinhalFalls.esp [Version 1.0.1]AB xulAspenWood.esp [Version 1.0.2]** xulAspenWood Vwalk.espAC xulSkingradOutskirts.esp [Version 1.0.1]** xulSkingradOutskirts Vwalk.espAD xulSnowdale.esp [Version 1.0]AE Feldscar+Snowdale Patch.esp [Version 1.0]AF OOO-Snowdale Patch.espB0 Duke Patricks - HammerBlade.esp [Version 2.9]B1 Open Cities New Sheoth.esp [Version 1.1]B2 Open Cities Outer Districts.esp [Version 3.5.5]B3 Open Cities Reborn - Full Merge.esp [Version 0.6.3]B4 OCC-ULCH-Patch.esp [Version 2.2]++ OCC-COBL-Wells.espB5 NRB4+UL-II+LtPD+OCOD Patch.esp [Version 3.0.2]B6 OCLR+ULBWForest Patch.esp [Version 1.0.2]B7 NaturalVegetation.espB8 Harvest [Flora].esp [Version 3.0.0]++ Harvest [Flora] - Shivering Isles.esp [Version 3.0.0]++ Harvest [Flora] - DLCVileLair.esp [Version 3.0.0]B9 Harvest [Flora] - DLCFrostcrag.esp [Version 3.0.0]++ Cobl Bookplacement.espBA HUD Status Bars.esp [Version 1.2]BB EVE_ShiveringIslesEasterEggs.espBC kuerteeInventoryIsABackpack.esp++ GotNoClass.espBD P1DkeyChain.esp [Version 5.00]BE PersuasionOverhaul.esp [Version 1.43]++ PersuasionOverhaul_OOO.esp [Version 1.2]++ PersuasionOverhaul_MMM.esp [Version 1.2]BF ReneersGoldMod.espC0 Salmo the Baker, Cobl.esp [Version 3.08]++ ScriptIcon_Replacer.espC1 Soulgem Magic.esp [Version 1.0]C2 Storms & Sound - Bank of Cyrodiil.espC3 Storms & Sound - The Lost Spires.espC4 Toggleable Quantity Prompt.esp [Version 3.2.0]C5 Roleplaying Dialogues.espC6 Quest Award Leveling SI.espC7 Quest Award Leveller.esp++ Quest Award Leveller - Battlehorn Castle.esp++ Quest Award Leveller - Vile Lair.esp++ Quest Award Leveller - Mehrunes Razor.esp++ Quest Award Leveller - Knights of the Nine.espC8 OWE&P.espC9 RealisticForceMedium.espCA RealisticMagicForceLow.espCB SupremeMagicka.esp [Version 0.90]CC SM_ShiveringIsles.esp [Version 0.86]++ SM_DLCSpellTome.esp [Version 0.80]++ SM_OOO.esp [Version 0.89]++ SM_MMM.esp [Version 0.89]++ SM_COBL.espCD SM_EnchantStaff.esp [Version 0.80]++ SM_VanillaSpells.esp [Version 0.86]++ SM_UnlockSpells.esp [Version 0.70]++ SM_NoSpellLights.esp [Version 0.70]++ SM_Scrolls.esp [Version 0.84]++ SM_SigilStone.esp [Version 0.83]CE MidasSpells.espCF OC+Midas Magic Patch.espD0 Midas OscuroGems.esp++ Midas Betterholy.esp++ Mart's Monster Mod - Midas Creature Ingredients.esp++ Midas Tigernolevel OBSE.espD1 Midas BeastFortify Fix OBSE.espD2 Friendlier Summons.espD3 EnchantmentRestore.esp++ EnchantmentRestore_Wells.espD4 StealthOverhaul.espD5 DD_ProximitySneakPenalty.espD6 Morrowind Lockpicking.espD7 RenGuardOverhaul.espD8 Duke Patricks - Combat Archery.esp [Version 3.4.1]D9 BetterBlocking.esp [Version 1]DA Duke Patricks - Near Miss Magic And Arrows Alert The Target.esp [Version 7.1]DB Duke Patricks - Everyone Or Just Vampires Now Bob And Weave.espDC Duke Patricks - Actors Can Miss Now.espDD Duke Patricks - Fresh Kills Now Alert The NPCs.esp [Version 4]DE nGCD.esp++ nGCD Birthsigns.espDF nGCD Oghma Infinium.espE0 ProgressMBSP.esp [Version 2.0]E1 ProgressSBSP.esp [Version 1.0]E2 ProgressRBSP.esp [Version 1.0]E3 ProgressRacial.espE4 ProgressArmorer.esp [Version 1.0]++ Immediate Character Generation.esp** Cava Obscura - Cyrodiil.esp** Cava Obscura - SI.esp** Cava Obscura - Filter Patch For Mods.esp++ Item interchange - Placement for FCOM.esp [Version 0.78]++ Item interchange - Placement for Frostcrag.esp [Version 0.78]++ Item interchange - Option, Ingredients in Bulk, reduced.esp [Version 0.78]++ EVE_KhajiitFix.espE5 1em_Vilja.esp [Version 2.3.2]** 1em_Vilja Vwalk.esp++ 1em_Vilja OOO FCOM Fix.espE6 Cobl Races.esp [Version 1.52]E7 bgMagicEV.esp [Version 1.7EV]** bgMagicEV Vwalk.esp++ bgMagicSpellTomes_for_WryeBash.esp [Version 1.68EV]++ bgMagicItemSigil.esp [Version 1.68EV]++ bgMagicEVStartspells.esp [Version 1.68EV]E8 bgMagicBonus.esp [Version 1.7EV]++ bgMagicEVAddEnVar.esp [Version 1.68EV]E9 bgMagicEVPaperChase.esp [Version 1.68EV]EA bgMagicAlchemy.esp [Version 1.57]EB bgMagicPotionNumberSoulGemValue.esp [Version 1.68UV]++ Cobl Races - Balanced.esp [Version 1.52]EC Automatic Timescale.esp [Version 1.1.1]** [GFX]_Initial_Glow-all.espED Duke Patricks - Magic you can believe in.esp** bgMagicEVShader.esp [Version 1.7EV]++ bgMagicShaderLifeDetect.esp [Version 1.68]EE bgMagicLightningbolt.esp++ Visually Realistic Deadly Lava.esp++ Duke Patricks - BASIC Script Effect Silencer.espEF Real Hunger, Cobl.esp [Version 1.6.1]** NRB4 OCReborn Road Record.esp++ CoreRandmonClothing4Npcs.esp++ Cobl Filter Late MERGE ONLY.esp [Version 1.53]F0 Cobl Silent Equip Misc.esp [Version 01]++ OOO Harvest Containers Filter patch for mods.esp [Version 1.03]** All Natural - Indoor Weather Filter For Mods.esp [Version 1.0]F1 Bashed Patch, 0.esp
Hope I'm able to help.
Artorius.