Looking in to a fairly new system, Armor RV Roof Sealant System. I have a one piece fiberglass roof with end caps mating to roof section and of course along the edge of the roof section where it mates to the sides of coach. All of these joints are potential water leaks.
The Armor RV Roof System is the latest technologies in liquid sealants. They also reseal around all vents or other items that are coming through the roof like the dish wiring, etc. Note that the System can be applied over any style/type roof. They claim sealant is very reflective which involves lower temperatures in the coach.
Armor Roof System will come to your location. Takes about 2-3 days (depending on weather conditions) with some drying time during the process. Lifetime written Warranty that is transferable at no charge for the transfer to new owner.
I have a 36' NRV model 5535 and their est. was $4,500-$5,000 (if added time needed to properly prepare the roof).
2004 NRV Dolphin 5355, 24' Pace Shadow trailer, inside is a "2011 Hemmings Muscle Machine of the Year" and 2011 Reno, NV. Hot August Nights "Best Restored Stock Car", 1970 Olds F85 W-31, Rally Red, 4 speed, 1 of 5 in this color, only 207 built