"So my first question is: What are you guys using for heat shielding?
My second question would be an extension of the first. If you haven't found a good solution, can we come up with a good solution? I've done a little bit of research on heat shielding tape, but it seems like any decent product I want to try is sold as rolls of tape, costing hundreds of dollars. I don't want to spend $500 on 45 feet of heat shielding tape if all I need is 1ft, only to throw $480 worth in the trash."
You asked for solutions, and many have provided you with some, but the only solution you seem interested in is yours. IF you were doing a museum quality restoration, I could understand, but then why use something on a quad that will never run. I'll offer one more solution and then I'm done, using 3/16" large flange pop rivets, and some T-0 aluminum, make a heat shield the size you need. Space the aluminum off the plastic with some 3/16" washers, allowing for an air space between the layers and that will take care of it. Best of luck
desertR