do a search on this topic, lots of info on this site
1. Bilstiens shocks for smoother ride
2. Anti sway bars by Roadmaster, etc which connect box to chassis better for stability.
3 Steering stabilizer which holds front wheels in straight line to help stabilize steering.
4. air bags only help more for towing and heavier loads in back
steering stabilizer would help most for your situation but all three work together and really do make a big improvement despite what others may say. cost about $3K for all.
5. then have it aligned because if you have it aligned first and then do the mods, it might throw alignment off .
i had the exact same problems with my first unit. once I did the research on this site and did these mods, it drove beautifully.
you will only be able to smooth the ride out so much. recommend a good set of bilsteins or other shocks first. air bags are to help when towing or more weight in rear but wont necessarily give smoother ride, same with helper springs. sway bar will help with leaning but wont smooth out ride. the truly smooth ride only comes from a full on air suspension like on the diesel class a's. thats different from air bags. its too expensive to put a true air suspension on a class c, although it can be done. some ambulances, vehicles for handicapped, etc have it. the ride in a diesel class a is a world of difference, but so is the price.