Right now, you hard code the carcass processing code/drops directly into the Meat Hook TE. I would propose adding an interface, Carcass (or ICarcass if you like that style MC uses), which adds the methods returning lists of ItemStacks (referred to in the code base as returns) for each progression stage (skinning, organs, sawing, and finally butchering). Then, of course, you would remove all of those hard coded lists with calls to the interface.

Looking a bit more, we'll need an API for rendering, too.

An API is planned.