We haul a Lance 845 on our 2500HD 4x4 6.0L Chevy easy enough - altho we live on Florida, which is flat, we head to Blue Ridge and Rocky Mountains a couple times a year. It hauls those mountains fine too ...
We anticipated adding extra springs or Timbren, but have not found it necessary at this point. We might add new shocks and maybe a rear anti-sway bar before our next trip, but that's just because it will ride better not because it feels unsafe or wobbly. Truck is 2015 with 48,000 miles, mostly hauling the camper, so not like any issues are bothering us in our travels.
The 845 is a nice, well equipped camper with good sized tanks. Our DRY weight = 2780 lbs, and 8'6 fits our Short Bed just fine. We pack light, and keep our tanks low when traveling, and fill up when we arrive, dump just before we leave camp.
Those other Lance models are the same size, but lighter and a little less equipped, I believe.
Lance has extensive dealerships if you need any parts - altho most RV equipment is the same manufacturer anyway, Fridge, Pumps, Range, etc.