Hi,
Air bags in your case would 'stiffen' the ride. If you think about it, the truck rides kinds 'solid' when there is no load on it. Once you add the 2,000 pounds of weight to the pickup, it will soften the suspension by pushing down the springs a bit, and not ride so much like a lumber wagon. By inflating air bags, you bring it back to the unloaded height, and will make it 'stiff' again.
Now installing something like a air ride kit, where 1/3 of the factory spring is cut away, then replaced with a steel bar, and a air ride suspension is installed, and most of the weight is then transferred to the air bag, it can take up road vibrations, and pot holes with ease, and will soften the ride a lot. It will take it from lumber wagon suspension to something much softer.
If I ever get a F-450, I would probably have the suspension kit where 1/3 of the spring is cut off, and a air bag is installed to take on the load and smooth everything out.
Fred.