Ride Control by AIR LIFT . . . .
I installed this kit (Kit No. 59561) because when putting luggage, tools, etc. into the bed with a camper shell on it, the headlights irritated oncoming drivers. I got a "T" for the air line, & put the valve at the license plate hole on the rear bumper. I keep 20 lbs of air in mine all the time & the ride is still really good (don't notice any harsh ride).
It was really easy & inexpensive to fix the ride/load problem.