I wondered about trying to find a leak when I got my trailer. After I was finished I found 11 separate and different leaks from the entry door to the front of the first window forward of the door. I decided to do all the maintenance and eliminate leak points that way. I replaced the 3 roof vents,air conditioner, removed the television antenna, installed sewer vent gaskets, sealed all the seams, replaced all the window and door gaskets, found and fixed 5 missing rivets, sealed the awning rail, sealed the rub rail, replaced all the clearance and running lights with new fixtures with gaskets, butyl sealed all the wire entry points, and fixed one leaking skin lap joint.
I didn't have another leak until the new plastic vent fan flange cracked. I sealed that with Vulkem and haven't had any leaks since.