My saburban starter while not turn over after towing with travel trailer for awhile. Between us and our mechanic and our rv mechanic thought we covered everything. Don't know what else to do?
Can you define "covered everything"? What are the symptoms? Does it just click, or do nothing at all? Does the starter work after the vehicle has sat for a while? Years ago, Chevrolet had problems with the big block engines overheating the starter after running for a while. They would not crank, or cranked very slowly. After sitting long enough to cool, they worked fine. They installed a heat shield between the starter and the exhaust pipe to cure the problem. Perhaps your Suburban's exhaust is getting excessively hot while towing the trailer, and causing the starter to overheat.
Long time ago you could wack the starter a few times to unstick it. Also there were problems with the starter solenoid getting fried.People used to put a relocation kit on to get the solenoid further away from the exhaust.
Since you're towing a travel trailer with it, is it possible you have some kind of electrical issue with the wiring going to the trailer that drained the battery?
Answers
Perhaps your Suburban's exhaust is getting excessively hot while towing the trailer, and causing the starter to overheat.
More details/symptoms would be helpful