An air bag setup to support your load ?
I highly suggest you Air Lift loadlifter 5000. It is a very strong product. hasn't seen a bag fail yet. They can hold up to 100psi of air, and beleive me, 100psi is always way too much. You'll be far overweight before you air bags won't be able to support it.
Along with that, I suggest also a Wireless AIR (part number #72000) compressor system. A 12v electric compressor with electronic valves. You just have a remote in the truck, allowing you to inflate or deflate the bags, together or one by one. The system always monitor pressure, so if there is a leak or the truck hasn't been used for some time, at startup the compressor will adjust de pressure automaticly, and even when you are moving too.
I've tried some other brands, and airlift is always the greatest product. I install a lot of these at my job.