Totally get the questioning of painting a fiberglass roof.I have the same streaking problem(which is quite bothersome) and was just trying to maybe trouble shoot with a good rubber coating to stop the running once and for all and to also stop any deterioration by UV rays to the fiber glass.Leaving it alone for now as its had a good washing and a coat of zip floor wax to hopefully stop the running (white lines).Peace to all,Happy travels and thanks for being on this forum.This thing is priceless.