Here is a picture of a similar repair I did on my wheelwell over 4 years ago, once finished I spray painted the aluminum black, I used vulcum it has held up great.
Originally Posted by Canoe stream
Hi Steven -- Welcome to the Forums!
Don't have a picture but a plastic wheelwell liner on my Argosy had two problems -- a puncture and about a 7" crack coming up from one edge. I shaped a piece of aluminum sheet and pop riveted it over the areas with Sikaflex 221 caulk to seal the edges. Silicone caulk will not work up against aluminum. You'd never notice the patches unless looking real hard.