OP wrote:
As to the tire wear....checked online and found average TT tire life is anywhere from 5,000 to 12,000 miles. The tires on the camper are still the original tires and have 15,000 mile. This doesn't indicate to me that there is a problem with the axles.
Sounds kind of "nuts" to me to think that's the expected mileage. I have averaged over 40,000 miles on each set of tires on my Rockwood and would CERTAINLY think there was something wrong if tire wear showed up at 15,000. I agree with your factory rep that if the tank had fallen out it would be skidding down the road somewhere but depending on how it's attached the plastic CAN bend and become distorted. Might be a good idea to pull the belly pan and check it out but save that for sometime when you have nothing better to do LOL.
Good luck / Skip