I've been thinking of going with these:
Heavy Duty Front and Rear Coil Springs for Dodge Ram 1500 ? 5500 and D250/350 Pickups
Might even put the airlift bags in them depending on how my horse trailer makes the truck sit when loaded.
These are what I use. I had the same problem, with a work truck, but the springs really helped out.
I prefer the springs to the airbags, they just give me better piece of mind.