[bobinbc]

I believe the solution there is taller cups on the top of the bags. This will give you the same ride height at a lower pressure. Unfortunately I don't know how much higher you'd need to make them. You need to find out.
I think I would drive the truck onto some 2x10 blocks, enough that the exhaust wouldn't bottom out when you air it right down. Now measure your front ride height. Let all the air out of the front, then start airing it up again. When it starts to lift, push down on the bumper to see how stiff the ride is. Keep lifting 1/2 inch at a time and checking how stiff it is. When you find the sweet spot lower it 1/2 inch and measure. The difference between this measurement and your initial one is the amount you need to add to your cups. Do the same for the rear.

At least that's what I think.....