Wild West challenge - character design

I want to do mashup of Texas chainsaw massacre, Resident Evil with skinwalkers in Wild West. It suppose to be dark horror, maybe even Lovecraftian feel. Very simplified plot would be a town like Innsmouth but instead people turning into monsters, its monsters turning into people. But don't quite get it, how to human. Outlows spent too much time in their animal forms, and in human skins they can't help to act more animal-like. Skinwalker gunslinger, is just skinning gunslingers to posses their skills, stooped caring for human correct anatomy, having 3 arms and deformed body. Townfolks are the one who help skinwalkers, butchering humans and sewing human skin for skinwalkers. Shaman with daughter is here to fight skinwalkers but more in esoteric way. I have no back story for lawmen yet buuut rule of thumbs in good horrors is to not explain everything right? :D