Rig Instance?

Hi,

I have a non conventional character (a mode shifting robot with sliding joints. think Bastion from overwatch) that I need to be able to use humanoid animations. I regularly use humanoid animations on it so I can share with other characters, and when I change its mode I swap the character out with a generic rig. Is there a cleaner way to do this. Ideally, I'd like to do this all in one rig, but the humanoid settings won't let me access translate values.
Duplicating the rig is the workaround I found, just to get around this, but that creates extra junk in the game, one more file to add to the size of the game. Is it possible at least to reference a rig as a different type?