Post maiden voyage, deciding on modifications?

Air bags have the advantage of being highly progressive and easily adjustable, which springs (steel or rubber) are not.

If you ever run the truck without the camper, I'd use airbags, and adjustable shocks like the Rancho 9000. You just can't make a non-adjustable suspension work well with 2000 lbs on it empty and 6000 lbs on it loaded. If you tune the steel and rubber to work well in one condition, it will work poorly in the other.