Sorry Rich, but that is one of the bad things about a gasoline motorhome. I had one and I know what you are talking about. About the only thing you can do is not to have too much air pressure on the tires, but you still want enough air pressure where you will not damage the tires. Some RVer's have so much air in the tires that they become hard like a rock.
Now as to putting air ride on a gasoline coach? I have never seen it, but I have read on the class C forum that some have installed air bags to the big Super Nova's. So maybe they do have them. You have to have some kind of a compressor like diesel coaches to supply the air. It sounds to me like a lot of money to invest on a gasoline motorhome.
Mine used to have the Firestone air lifts, but those are not to give a softer ride, they are for more carry capacity and help the leaf springs take some of the load off that way your motorhome is not dragging every time it hits a dip.