I used some black construction paper I had laying around. That or some roofing paper (aka tar paper), although that might be a bit thick.
As far as that stud that's spinning, that's going to be tough. IIRC those strips are stainless/chrome wrapped around an inner steel strip, and you'll mess the bright part up trying to get it apart. You might be able to hold the stud on the protruding end with some padded pliers so as not to mess up the threads and get the nut spun loose. But the problem is it's behind the dash and a PITA to get at in the first place. I think your best approach is to break that strip loose (carefully so as not to damage the dash), then hit up the stovebolt collective for a replacement in the swap meet.
If you meant epoxy the strip in place, I don't think I'd do that, but if you can get the nut off and the stud is not damaged, you might be able to epoxy the bolt to the strip to keep it from spinning again. If you can salvage the strip undamaged, use something like windshield sealer (urethane hardening style) to reattach. Just a dot at the stud positions should do it, with some tape to hold the strip in place till the sealer hardens.
My condolences on your problem. Been there in similar situations.
