After tinkering around for a while (and testing many things out) I have ended up creating an evil human-variant civilization known as the Necronphesh. Some of my inspiration for this civ entity comes from Warhammer fantasy, specifically the Nehekhara. This is a rather bad variation of humans; in world generation they typically start of at-war with just about everyone. Thank you ethics tags! Makes the game so much more fun.
As a part of this mod I have created my own building and custom reactions for it, to allow the Necronphesh to craft a much wider assortment of objects out of bone. Walls, doors, blocks, beds, etc. I am halfway tempted to do a serious play of this civ (after some more testing) with something along the lines of Reveredtour, built out over an ocean or lake for kicks. Internet Kraken's Diverse Creatures Mod would certainly make such a site more interesting.
Still tinkering with the best way to handle the slave caste of the Necronphesh, divided between making them their own creature type or having them as a subcaste of the civ entity. Will try out both to see how it turns out.