You should definitely weigh the motorhome. If you can get each corner, that's ideal. Not all scales weigh all four corners, you might have to settle for front axle and rear axle weights. Then check the tire manufacturer's specs on tire pressure.
You should also have the alignment checked and the ball joints checked. I noticed on our motorhome at the end of the year last year that the front was a little loose and figured it was time for an alignment. Turned out the ball joints were shot. Had them replaced, the front end aligned and the motorhome drives great now. No movement at all.
Our motorhome came from the factory with front and rear anti-sway bars. It amazes me that anything larger than a mini-suv comes from the factory without both front and rear anti-sway bars. A rear anti-sway bar will help with body roll and make it feel more stable.
-Michael