Steve,
To correctly answer your question, I would need to know what is causing your roof leaks. If the roof leak is from failed sealer (calking) at seams around the roof vents or skylight, you just need to reseal those areas, and possible paint the roof with something like the Rust-Oleum paint mentioned above to stop chalking and white streaks down the side of the coach. The same thing goes for leaking seals around the A/C units, just replace the seals.
However, if you are getting leaks from a porous section in the fiberglass roof, you need to coat the roof with an elastomer coating like the Rhino bed liner that is used to coat pick-up truck beds. There are several brands of elastomer coatings that all do pretty much the same thing, and the price can vary widely depending on how extensively the job is done. If you remove the A/C units and all roof vents and solar panels, you are looking at a lot of labor to apply the coating. But if you do don't think that the leaks are in those areas, you can just apply the sealer in the exposed roof areas for much less of a labor bill.
Gerald