I used Dicor Fiberglass RV Roof Coating
four or five years ago and all I've done to it since then is wash it twice a year when I do my semi-annual inspection. Surface preparation before "painting" was a real PITA but it appears to have been worth it in the long run. I've been extremely pleased with the results.
One other thing that should be mentioned is that the surface is also slightly textured now and isn't nearly as slick as before it was painted which is a huge plus for an old, overweight fat guy!!