I also had kind of the same idea:
I ordered a wood skin from Slickwraps (which still didn't got here to Germany after 22 days since ordering, but that's another story...), and to show it of I bought the Ultra Hybrid. But the clear back is actually pretty slippery, and the TPU on the sides unfortunately isn't really grippy too.
So I thought of buying the Neo Hybrid and cutting away most of the back to actually get a "real" Bumper since there aren't any quality ones to get in Germany
Another idea would be to get the skin not on the phone but directly on the case, and as long as the skin isn't black, the "nexus"-logo cutout would actually make it have the "nexus"-logo on the back, know what I mean?
Sent from my Nexus 5 using xda app-developers app