I too have a problem with leaking in that same area. Driver side rear corner of fantastic fan. The trim frame has turned color from water damage and the fastening screw rusted thru. Not much water appears, just enough to be annoying to my wife who gets hit in her position.
I've tried re-caulking all the rivets and it sometimes works for a while. Did not notice any water this summer camping but now that it's starting to turn colder the water has returned during heavy rain. I check the bed after the rain and look for wet spots.
Caulk might be shrinking in the cold revealing places for water to go.
It's interesting that we have the same leak in the same position. My wife says also the leak was happening before we installed the AC in 2013. So.........eliminate that? The escape
hatch has lots of rivets so it could be coming from there. It's just in front of the Fantastic Fan. The rat fur never seems wet from a water trail.
I will find the source even if I have to tear the whole ceiling apart. Well maybe.............
Hopefully someone out there has solved this problem that happens to only Scamp Deluxe 13 and 16's?