I'm new to the forum starting today. My situation is similar to VAredRAM's except that I have an '09 Ram 3500HD 4WD SRW pickup. I made an assumption that I'd be able to carry the AF990 w/o any issues...
The simplest solution involves checking to see if you are engaged with your overload spring. 90 psi with camper only seems pretty extreme and the more pressure you have, the higher you are riding over the overload spring. Adding the stable loads to ensure spring engagment is simple and inexpensive.