OK--I spent most of the day troubleshooting this with the RV people.
A very nice parts guy spent a lot of time looking the water heater over--adjusted the airflow etc. etc.
I purchased a new contoller to install, since after much testing there was still just lukewarm water.
They originally asked me if a bypass valve had been installed on the trailer---so I went home to look for that--no I didn't see one.
I started to get ready to install the new controller. I noticed when I went to dump the water in the tank it was VERY HOT!
That led me to another search for THE valve--which is of course there (part of the original installation.
Turned the valve and voile! All the hot water you want.
After spending the whole day getting ready to take a hot shower--got everything set up, walked in the door of the house and after 5 days of no power the lights