We have a 2003 Keystone Springdale 27'. After the last snow we discovered water was leaking from the seam on roof near front, where the rubber (?) roof meets the aluminum. It's the only seam on the ...
I would call an independent rv tech and ask for a price. If you dont know one, contact a local campground where you know the operators and ask them for suggestions for one.
The edges at that age should all be closely examined and any questionable caulk cleaned out and replaced before coating. And a lot of folks swear by eternabond. You may want to look into it as well.