Air bags (as in air helper springs, like Ride Rite ones et al.) will not lower the suspension on the gas motorhome unless other changes are made at the same time, which probably would be inadvisable. Obviously replacing the entire suspension with an air suspension is a different story.
Maybe you can get and install a lower profile air conditioner? Maybe if the ground isn't perfectly level you could fit in if you back in vs. pulling in head on (or vice versa)? Maybe you could lower the floor of the barn, or raise the building up by a few inches on its foundation?
