If the leak is around the vent housings I would pull them and replace the butyl tape (strip caulking) that is under them. Reinstall them and when snug you the use a good butyl, self leveling caulk to cover all of the edges and the screws.
Most any RV store should have the self leveling chaulk. Go on the top and look. The rubber will be softer and have a rougher surface. Aluminum will be more like tin and fiberglass will be smooth and hard.