We too have had excellent results with Rancho adjustable shocks that all but removed all of the sway. Rear airbags to restore proper ride height to the pickup bed and very importantly levels the rig from side to side. And lastly the highest rated wheels and tires that the budget allows. RV tires tend to wear out by aging rather than tred wear, so inspections for dry rot and cracking are needed. Maintaining adequate tire pressure is also high priority.
I think that the order of importance is wheels and tires first, air bags next and so on. We discovered that less is best with air in the airbags, with average loads 65 psi passenger side, 55 psi drivers side, for our very heavy rig has been fine. Too much air in the bags makes the ride way to stiff.