Cool idea for a mod.
Some ideas:
-Give the vampire a bonus to movement speed, the bonus should increase the more hungry he gets.
-Add a charm skill (once per combat), the chance to set it should decrease the more hungry the vampire is. After all a frothing starving bestial vampire desperately craving blood is not very charming.
-(Wacky idea) a vampire can't use the bedroll, but can use a coffin.
-Should not get any bonuses from food and healing potions only heals 50% of their normal value.
-Can't have the rested status
Should he be considered an undead, meaning the effects of healing and poisons are reversed?