All necromancers have Alchemy due to it being one of the factors to be able to further enhance your animated undead. Thus I reckon it'd be a fun roleplay opportunity and fun 'daily thing to do' to be able to create varied corpses through alchemy. Could you make some (high DC) formula's for this?
I recommend making the corpses unable to be deposited into House Baharu for favor.
There already are :)
Not talking about 150lbs corpses that the spell Animate Dead does not work on
I think that given the randomness of Alchemy etc, a good source of corpses could be a reuse of the existing Skinning system. Plenty of Animals leave reliable bodies that can be Skinned or Butchered. Rot Wardens can consume an Animal Corpse for buffs.
It could be relatively simple to add another tool that harvests them and drops animatable Corpse items into your inventory. And unlike Alchemy, it makes Necromancers move around hunting rather than hide out.