Bill, I am surprised your question has set idle for several days. Had the same/similar questions several weeks ago and half the forum chimed in. Every one had an opinion and were passionate about their solution. I will reprise my solution and let the opinion games begin!
I washed and waxed our fiberglass roof with various recommended products, but they just didn't seem to hold up to our southwestern sun. Got tired of chalky streaks down the sides after heavy dews and light rains. (Not here, we have to drive far in search of rain)
Finally, with no small amount of trepidation, decided to try ZEP High Traffic Floor Wax. Applied two coats with a Swifter dry pad (well, wet with ZEP). Nice look. Not high gloss, but a satisfying satin sheen. Not as slippery as the other products either - wet or dry. Just rolling over the two year mark, and it still looks great. Had rain and dew last month up at the North Rim. Still no white streaks. Nor from the monsoons here this month. After the monsoons, I may apply another coat, but not sure it needs it.
Although it is easily remove with ZEP's proprietary remover, be advised two coats of ZEP leaves a film about as thick as plastic wrap. It also bonded to all the various roof penetration sealants. I'm calling the film thickness and bonding a plus.
And there we are! We report, you decide!
Fair Winds and Following Seas