Noisy Demon trunk lid?

Here's what happens when I push with my thumb on the trunk lid.
The smooth outer metal sheet is elastic. It's noisy and also hits the inner bracing (the space between them is thin, maybe 2 or 3mm)
The median rib on mid '71 trunk lids is probably how Chrysler fixed the problem.



Now, how correcting this problem?
I though about using expansive foam but there's no way to access the noisy area.
Noise.jpg
Another solution : drilling a little hole into the sticker and the inner sheet. Sticking a nut and with a screw, slightly pushing onto the outer sheet to immobilize it and by the way turn it silent.
I don't know if I'm very clear but I do not see any other solution.