Perhaps I'm misunderstanding the question, but I think you may not be picturing how the camlocks function correctly. On most installations I've seen, including mine, the receptacles get riveted to the airframe at the firewall and the parts (the studs that you screw 1/4 turn) that are installed on the cowling itself are simply held with clips. I didn't even install the clips until after paint, the screw/studs simply drop in to a properly sized hole through the cowl into the receptacle. The collar around the stud is bigger than the hole in the cowl and the pressure on collar is what holds the cowl. There's no riveting needed on the cowl itself.
If you hunt around you'll find pictures of the installations that will help it make sense. I installed a strip of aluminum that was cut in scallop shapes to make a "shelf" to rivet the receptacles to the top of the firewall. The back of the cowl rests on this "shelf" and the studs go through the back of the cowl into the receptacles.
Jeremy Constant
