No offense intended, but that camper rental outfit should consider installing load levelers on their camper tongues and renting them with the corresponding hitches. I know 99.999% of the members here have gone coil spring in the rear, but I prefer the bags for this reason (and because mine is, sadly, an asphalt queen).
I think it's mostly my fault for loading up the camper to the hilt especially at the front end. I've since upgraded the suspension to a 4 inch lift with Xtra heavy duty coils in rear. We travel fully loaded with 4 kids so things get kinda heavy