Whitlow. I have a fiberglass roof. I will describe what I did and why. Likely someone else will come in with a different method. I'm good with that. Makes for a good forum. "We report, you decide"
A couple of years ago, we stripped our fading decals and had a local guy paint them back on. Along with that, we had him refinish the rounded roof edges which are infamous for loosing the clearcoat. Shame on me, we drove off for our fall trip without noticing he silicone sealed the side roof edges. By the time we got back it had already failed. (yes, did speak to him, but that is another post)
Devoted many hours to scraping and digging out the silicone. Broken pieces of CDs seemed to work better than metal or plastic putty knives. There are products out there that claim to remove silicone sealant. Not my experience. I was happiest with mineral spirits and elbow grease. Followed that with a liberal wipe down with 91% rubbing alcohol.
Many opinions about proper sealant. I used self leveling DiCor. (sp?) Pushed the nozzle deep into the trough between the fiberglass sheath and the aluminum drip channel and applied liberally. The fiberglass will tend to spring back, squeezing up a satisfying bead. (takes a little practice). I let the bead dry overnight and the next day trimmed it with a razor knife.
I had read that Winnebago has been repairing roof radius hairline cracks by applying eternabond tape along the entire edge. Liked the idea. Did not seem to me to be a one man job. Stand by for controversy
! So I covered that joint with black 2" Gorilla tape. It has been amazingly durable. I also use it on our entry door edge and cargo door lower edges to prevent stone chips, etc. Luckily, the black tape complements our coach color. Pics attached. Took the roof pic a few minutes ago. As you can see, after almost two years, the tape looks new. Applied the tape first, then covered the ends with dicor when I sealed the front and rear caps. The door edge pics are about a month or so old, but all the tape was applied at the same time
Fair Winds and Following Seas