Dutchmen Sport, thanks for your advice. Remember this is occurring UNDER the mattress. We keep a fan running inside the rig all the time, whether the AC is on or not. But you're right, this isn't a leak, it's condensation. Never had this problem so bad before, but this summer has been a witch with humidity.
2oldman, that mold scared me plenty. We really cannot let this stuff reappear, anywhere!!! Thanks for your warning!
The pipes under that mattress looks tacky, but as long as it works, they stay until someone has to sleep up there.