Just a heads-up: this one might be a bit convoluted. Basically, I want to be able to make my character a vampire lord (I have the Dawnguard DLC so that's covered) while still have NPCs use race specific dialogue. I know that becoming either a vanilla vampire or a DG vamp lord changes the character's race, eg. from DarkElfRace to DarkElfRaceVampire so normally NPCs no longer use lines referring to the player as a Dunmer/Nord/whatever but is there any way around this, either with console commands or mods?

I guess I could add the V Lord ability with console commands but I'd like the whole package: glowy eyes, fire and sunlight weaknesses, fluctuating powers depending on how long it's been since feeding and so on and I don't think player.addspell will do all that and prevent everyone from forgetting I’m a Dunmer.

Generally the Vampire versions of each vanilla playable race will still get the same comments from NPCs that their base race will - though you may begin to hear enemy Vampires refer to you as a Vampire in addition. Perhaps the vanilla game may have problems with this, but USLEEP possibly fixes that problem.

I'd also suggest using mods like Better Vampires and Royal Bloodline if you are looking to do a Vampire Lord Character. BV has customization for how you'd like to play your character, and RB has enhancement of the Vampire Lord(more perks for the VL perk tree, access to the "King" or "Queen" version of the VL armor like Harkon uses with a new perk, etc).

The issue with the winged bat-like "lord" form is that it's not it's own race, it's a spell-based change effect just like the werewolf form is, and you'll always get attacked by friendlies in that form because it's treated the same as the vanilla stage 4 vampire.. so you won't be hearing much dialog at all with that form. The basic vampire race appearance (modified by Dawnguard) seems to be what you're after, and with wanting all the extra vamp stuff that goes with it, a few comments with no downside or blocked interactions doesn't seem like very much reason to avoid just becoming a vampire. You also won't be able to just add the vampire appearance traits to your character through the console, because they're contained in race-specific lists and only made available in your race menu if you are that race. You would need a mod for that.

*Feels really dumb.* It turns out I didn't have USLEEP installed. I mean, I'm not huge mod user but I can't believe I missed that. I'll try that and see if that fixes it and if not I'll try BV and RB.