I have some unneeded back skins, cape buff, hartebeest, and impala. Any thoughts on what to do with them?

Make pillows. Or have a strip of the skin sewed on a belt. I did the latter with a strip of zebra.
Check your PMs.

I used the back skins of my zebra and common sable in the side panels of the pedestals for their mounts. I will do the same with the back skin of my Roosevelt sable when it gets mounted.

My wife likes pillows. Buff wouldn't work well, but we have lots and lots of pillows. They actually are pretty cool.