I have an 2012 Allegro on a 24k f53 chassis. As many gas burners know this is basically a camper mounted on a truck chassis. I don't have issues with stability, but the ride is rough to say the leas...
On my 1990 p30 It had the rear springs replaced. It was starting to sag in the back. Well the springs did level it out somewhat. A couple of years ago I added air bags on the rear to bring up the ride in the back. I was surprised by how it softened the ride in the back. I keep about 60 psi in the back and it has just a slight rake to it.