Don't know why you wanted to rivet the metal down. Liquid nails will hold anything, veritually ... forever!
On my Chevy S-10 pick-up (1985 model), the front passenger turn signal feel out. Not just the lens, I mean the entire assembly. The plastic catches broke out and the thing was just hanging there under the bumper by the wires.
I picked up 2 tubes of Liquid nails. Put the assembly back in place and pumped everything full of Liquid Nails, except the hole where the light bulb fit. Well, after 10 years, the rest of the truck was falling apart, but that turn signal assembly was still in "there" rock solid, after 10 years of rain, snow, salt, heat, cold, and lots and lots of vibration and bouncing around!