My vote is to try the airbags... either Firestone or AirLift, 5,000 lb ones. Probably best & certainly cheapest to get the bags installed with just manual fills first, pump them up to near max (100 psi) near home, and see if they make enough difference going into the drive. If they do, spend the extra bux for an on-board compressor and manual dash controls, so you can inflate them from the driver's seat. Mine provide well over an inch of lift at the axle, on a shorter lighter unit. Consider removing the rollers to increase the clearance if the bags come close to giving the needed clearance.
Be absolutely sure that if you do install the compressor and controls, you get the controls that allow _separate_ filling to avoid increasing sway. Mine have 2 gauges; you run the compressor to increase the pressure in both bags together, then can let out air from one side. That'll also give you somewhat limited ability to level the RV in camp (won't interfere with using leveling blocks as well). Be aware that there is a minimum pressure (10 psi?) that you have to keep in the bags when driving to avoid chaffing damage.
Jim, "Being politically correct means always having to say you're sorry, even when you know you're not."