If the area isn't completely sealed on the backside - i.e. you can put a piece of safety wire through the hole from the outside and find it on the inside - you can install a nutplate. Drill the holes for the ears and countersink them for 3/32" flush pop rivets. Push a piece of safety wire through the middle hole, and string a nutplate on the wire on the inside, then bend the wire end over so you can then pull the wire back and get the nutplate up against the inside. Rotate the wire to get the holes aligned, pop rivet it into place, and then pull the safety wire out. Done!
I have used rivnuts in a few places on the -7a, but I have had several spin on me. It seems like you need a minimum thickness of the skin to really retain these things or you risk spinning them in the hole. The tab mounted ones no doubt work better, but I really like nutplates and use them wherever I can.
Mark Olson RV-7A F1-EVO Rocket