Yeah. I discarded those ideas since they kinda go against the spirit of the game. It'd be easy, but kind of trivial to stick with one full feral TF like that.
If you really want to, the best I could think of still doubles the amount of art needed—
You could have a setting to do anthro or feral. If you made it just visual, it'd allow you to have feral parts while not increasing the complexity of the actual game since it'd be closer to an asset swap than anything else and there wouldn't need to be too many changes in the code. That way, you could have mixed parts, but they'd all be feral / quadrupedal. You'd probably have to fiddle a little bit with some species like human or succubus— It might be better to flag that some specific parts can't be feral and just switch to anthro until you lose the illegal parts. (For example, human torso and legs)