More knowledgable folks about Host campers than me will come along, but in regards to your truck, figure you'll have a 5000lb plus load. Your rear axle rating by GM is sort of designed to match the gvw program of the truck. Actual rating by AAM is 10klb.
The AAM 11.5 axle is a very robust axle and now been in use by 2 of the big 3 for 15 years and counting in all 2500/3500 apps. In fact Ram just recently upgraded the 3500 drw rear axle slightly in the last couple years and GM I think? still uses it across the board.
Combine that with your dual rear tires and some suspension help likely needed and you have a capable vehicle for that camper.
Ideal rig would be a class 4 or 5 just like ideal for me would be a long bed 3500 or short bed dually.
If the truck is in good shape, well maintinaed and not a zillion miles, I'd expect good service from it with a large camper like that.
I've put a lot of hard miles (not that many, maybe 20kmi, but plenty of rough stuff like the Alcan) on mine, starting at 100kmi and the axle has held up great.
And it's still about the best you can do without going to a brand new F450 pickup, or any variants of 450/550 or 4500/5500 chassis cabs.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold