A fuse blows because too much current runs through the circuit. This could be simple overload condition (like a new addition to an already loaded circuit) but if nothing has changed, it was probably caused by a short of hot to ground or neutral. Consider the rain you mentioned, I would be most suspect of water in your wiring. Considering that 3 of the items you mention are roof/ceiling mounted, I would first suspect something near the roof. So that is where I would start, but it is rarely easy to track these things down.
My first inclination would be to inspect very carefully for any leaks around the A/C unit (once the rain stops). It is the biggest hole in your TT/RV roof. Pop the inside cover of the A/C and see if there is any sign of water making its way in. Also, pop the covers on the ceiling lights, take the bulbs out and make sure they are dry. The first indication of a leak in a friend's pup was actually water accumulating on the lens in the fixture.
While doing all of this, be very aware of your conductive situation (wear rubber soled shoes, and stay away from touching metal). Although 12V is not AS dangerous as 120, it can still give you a heck of a jolt if there is a short.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP