We have a 2001 Lance 1030 on a 1996 dodge 2500. Our truck does have the factory upper load springs and rear sway bar that comes with the camper package. I weighed the camper at the local farm supply store. With a full tank of water but no food or other camping supplies it weighed around 3600 lbs. It does have a generator and A/C for extra weight. Mine is a aluminum siding model so may be lighter than the fiberglass ones.
On my 3/4 ton truck and LT265 Michelin tires I'm over the axle limit, way over the GVWR and pretty close to the limit of the tires when loaded up. I added upper stable loads and ride pretty level. I wish I had a dually and have been looking at them lately. Driving across Nebraska with a 40mph side wind was a handful.
With all of the being said a dually dodge would handle the load pretty well. Don't forget he may need to add the dually swing out brackets for the front jacks to the camper in order to get it on the truck.
I'm thinking he'll need the following to get the truck ready:
Torklift frame mounted tiedowns
Torklift fastguns to fasten the camper to the tiedowns
A lance camper receptacle mounted in the bed
Torklift stable loads, may not need these since you have air bags
Dually swing out brackets for front jacks on camper
Thick rubber bed mat
I lay a 2x4 across the front of the bed floor to keep the camper front hitting the back window of the truck.