You might want to check out the Sealtech RV leak finding equipment, and local vendors who use this equipment on the linked map:
http://rvleaks.com/testing-locations/
You might think about using Eternabond or Dicor roof repair tape on any leaking spots. It doesn't deteriorate quickly like caulk does. I did ALL of my roof seams with Dicor tape a few years back and no longer worry (much) about the roof. Of course, I am in fairly dry California.