I've been working out a similar method, actually, for my hand to hand mod, where selecting a particular "stance" will actually change the player's race (from, say, Breton to Stance1Breton) while the new race's entry points to a new behavior graph (from DefaultMale to Stance1Male) and I'm going through the different Behavior files and replacing any references to default animations with my equivalent custom animation, and replacing any references to other Behavior graphs with my new "stance1" versions.
I have not been Hex Editing the Behavior files for the weapons there is not much point if we are never able to edit these then its just wasted time and if we are then Its easy enough to rename the new animation files to something descriptive to purpose.
Is this basically what you're doing as well, or do you have a method that doesn't involve blindly stumbling around through packed behavior files?
Path of least resistance -> I'm only replacing the animation files -> the only Behavior FIles I am Hex Editing are the ones for my fake character actors for Paired anims and even then I think I am just going to give that up its a bigger waste of time then just replacing races for specific actors and reusing already available idle slots.
Will the hair/beards thing actually be a problem here? I was under the impression that when the race is forced to change via script hair, beards, horns, etc will stick around, even if they aren't available by default on the new race, kind of like when people take a nord and setrace themselves into an argonian, you can get a creepy argonian with blond hair.
Never sure exactly how the game is going to save your character when your playing as a race that does not support your current choices.
Though IC another incompatibility any mods that use SetRace in the manner that we are will conflict horribly as the scripts fight each other over what race is the current race and most likely have issues when reverting to default races...