Your truck already probably has enough miles to have worn out the OEM shocks that are usually tuned as soft as needed to feel good during short test drives on smooth roads near dealer. Replacement with aftermarket, some of which would be superior to OEM, may better control excess "sway". Good aluminum-bodied shocks will dissipate heat of damping motion of washboard roads. One trip across Mojave Road in our Rubicon destroyed a set of steel-bodied Bilsteins; I eventually went with aluminum Fox Shocks but extreme testing pending.
Shock or strut valving is selected to damp quick, high speed motions and separately to also control slower, wallowing-like motions. There are also different ratios of damping between compression and rebound, often a little less on compression to better absorb bumps than potholes and to avoid a jacking effect where repeated motions lift vehicle up before it can settle back down, something the failed rear Bilsteins did on our Rubicon. And, leaf springs may provide their own friction (damping) resistance to compression but snap back with little resistance to rebound motion whereas coil springs offer no resistance from friction in either direction. Coil springs therefore allow automotive engineers to better fine tune suspension via shock valving selection as the changing variable of how much friction a leaf spring is providing doesn't have to be accounted for. But, this means shocks do all the work of damping motion and may overheat and wear out faster on a coil-sprung vehicle with a camper or trailer on rough roads.
So, I wouldn't rule out the Ram 2500 if not overloaded and with good, firm aluminum-bodied shocks. Whether that or some other vehicle with leaf springs, you'll still have to decide use and percentage driving of truck with camper on vs off as to whether air bags (handles variable loads) vs firmer springs (for near full-time camper use) was appropriate. Of note, some air bags don't provide support through full wheel travel (like various glorified bump stops and jounce bumpers), and air bag support upon suspension compression goes up as a geometric progression (gets a lot firmer faster) faster than a typical coil spring, which increases support as an arithmatic progression. So, air bags add another variable as to whether or not your shock valving can damp motion. That's why air bags are best inflated just enough to help out without shouldering too much load on a way too-soft suspension, something more likely on a half-ton truck.
As for "sway bars" (AKA anti-roll bars, etc), if you already have an OEM one try it out as-is, as thicker would help you corner flatter and help with crosswinds more, but at the expense of a rougher ride and even reduced traction on rough roads. Also, too thick of a rear anti-roll bar might induce oversteer, where the rear slides out when cornering before the front does, only good for certain types of racing.
Vehicles are always a design compromise, and you may have to modify anything for your needs. I even had to have one more leaf added by Deaver to main leaf packs of our 2020 F350 with OEM camper package for our Hallmark Ute, and that truck was over a thousand pounds below GVWR with loaded camper. But, it rides and handles far better overall (but a little rougher on USFS roads) with camper but too rough on rough roads without camper (like one-ton trucks used to before '80s), which is rare.
