This particular Skyrim game has crashed / frozen a total of six times. After each time, I went over to the logs folder to check which script was last run. Five out of the six times it was DLC2InitCrossDLCScript.psc that was last run, which is a script from the official Dragonborn DLC. That's some coincidence, enough for me to strongly feel that those scripts are causing the crashes / freezes. Is there a known workaround to this problem? I'm already running the Unofficial Patch and Unofficial DLC Patches. For the other, single freeze the last script run was PlayerRiderScript.psc, which is probably in the .bsa file of Better Fast Travel - Ships and Carriages.

Just a thought, but have you tried disabling all of your mods and patches and maybe even starting a new game once they're disabled?
I haven't had this problem at all while running the Legendary Edition. I have mods, but I do not have the unofficial patches.

And if it works as it's supposed to once you disable everything, try enabling the patches/mods one at a time to find the culprit.

(Also, is it crashing a specific area?)