Box truck and Air bag assist

By the symptoms described I don't know if that'd help much. Sounds like the truck is just too light on the steer axle when empty.

 

Typical single axle straight truck ride. Air ride makes it worse. The bucking action is normal with the rear overhang and lift gate weight, but with air ride it gets amplified and side to side sway gets added into the mix. Thats why so many roll over easier than a tractor. I only own straights with spring ride and will never buy a straight with air ride. I don't like fighting that light floating steering characteristics and the row boat in the ocean feel going down the road.