The fiberglass roof is also a more stable surface to caulk against than many alternatives. On a fiberglass boat, removing and recaulking all the deck hardware every 10 years would be considered a very aggressive preventative maintenance schedule. Many go 15 or 20 years without much attention. The typical RV recommendation is to pour Dicor over it once a year. My BF camper purchased new in 1998 was sold in 2012 without a leak and no resealing since new. The one I have now is 8 years old, no leaks, no resealing from new.
