Ram might be my first preference too but I’m stuck on the the fact that somehow Ram can’t do better than a turn of the century transmission yet in their diesels. However the 8 speed behind the Hemi is a world class trans.
Getting a dually, you’ll have a legit 4klb + payload. I’d haul the camper before springing ( no pun intended ) for airbags. Put the combo together and see how she handles. Sway bar and possibly some stable load type deals may be all you need. If you do find you still want airbags, they’re a easy no drill, 2 beer job and I think the auto level/cab control feature is just extra complication and not necessary. If you’re hauling the same load then you won’t really use on the fly adjustment. No need. You can buy a set of bags for like $500 usd. I’d get basic u fill em bags and if I had to spend extra $, it would be for a quality onboard air compressor that would air up tires too. Or a small 120V air compressor that you can stash somewhere and use at full duty cycle to air tires and or bags as needed if you have jaunts with no camper. Or just need air.