Since rear air suspension install my 3500 "squats" 1/2 inch from empty ride height to fully loaded ... 6 in clearance to box sides to overhang on the toy hauler...
Turned left from an uphill street into a downhill lane ..."shouldda had 6 1/2 inches" I says, looking at the ding in the tailgate and box corner and scuff on the underside of the overhang... there is a skookum frame member in the trailer that is tougher than the tailgate/box tin :)
Coming back out we dropped the air and made it with 1/16" daylight to spare...