i had a leak in my fifth wheel last month during an extended bow hunting trip ( I know, murderer, redneck, yadda yadda). Made an hour plus trip to the nearest town to buy some flex seal for a quick fix.
Flex seal may make a boat out of a screen door, but DO NOT use it on a rubberized roof typical of rvs. I sprayed it on a seam that had cracked from sun, then covered the seam with a tarp. Leak stopped immediately (yep, tarp). A few days later, storm ends and I remove tarp. The entire painted area (1 can) peeled off my roof nicely in one piece.