Go after the poly sway bar bushings as 10forty2 posted. Very easy to replace.
Do a web search for "CHF" or Cheap Handling Fix. There's a very long discussion on IRV2.com. Not sure if your coach has the correct sway bar to move the end links. There are images posted on IRV2 so give you an idea what to look for.
You could install new heavier sway bars. Not too expensive but air bags will cost you more. Something else to check is if the leaf springs are worn out. Doesn't matter the mileage gravity works 24/7/365. What I don't know how to check. I would think measuring frame height once you know your weight but I don't know what the measurements should be. Maths is hard sometimes.
I do have airbags on my coach and they really didn't do a whole lot with regards to sway and such. They work great for leveling and such just not much concerning ride or sway control. Moving the sway bar end links had a very dramatic effect.