What do you guys do with the leftovers? I was thinking about adding it to some ground beaver meat?

that will work that's exactly how I deal with mine. Blend it 60/40 fresh preserved meat and ground tail chunks the longer you render the easier it grinds the bones become soft from prolonged saturation! Grind and preserve my fresh meat, then mix it up with tail chunks and grind again to get a well blended final product.

Thanks Tony!