There is one misconception from the first post that I would like to clear up:
Loading the camper absolutely does ***NOT*** increase the tire pressure. Not at all. So, your RV dealer is clueless too.
In order for the pressure to increase when the camper is loaded, the interior volume of the tire would have to be reduced. This does not happen. Where it squishes down on the bottom, it bulges out to the sides. Same volume.
The only way the pressure could increase is if the tire was encased in a rigid steel box so it could not stretch/squish/deform in any way.
I found it amusing that the ONE thing you were sure was true, couldn't be further from the truth.