The stock truck has a factory calculated maximum payload figure that is based on the leaf packs and wheels provided on the truck when it leaves the factory. The Duramax 2500HD SRW, 3500HD SRW, and 3500HD DRW, all have the same axle and wheel bearings which are rated by AAM at 10,900 lbs. but the factory rear axle loads are rated at 6000-6700 for the 2500HD, at 6500 for the 3500HD and 9300 for the 3500HD DRW trucks. The difference is in the extra leaf pack on the 3500HD and the two extra wheels with the DRW version.
No factory stock pickup is ready to drive down the highway with a heavy camper in the bed. Everyone upgrades the suspension and mods include adding Supersprings or air bags or stableloads or heavy duty shocks or anti-sway bars or all of these items. With SRW it is common to upgrade the factory tires to get more load capacity.
In addition you will need to add tie-downs, possibly a special superhitch for towing, wiring for the camper that includes an isolator and fuse. Many also rig a backup camera for the camper.
Don't expect a car salesman to be able to order a truck that is truly camper ready as they do not exist. The camper dealers know campers and can do some of the wiring and maybe install the tie-downs but that is about it.
If you want a turnkey RV vehicle get a motorhome. Then all you need to do is put gas in the tank and start driving.
Good idea to do more research so as to avoid costly mistakes like adding airbags for use with a camper.
Also don't blindly accept the sticker weight on a camper. It is likely to be 300-400 lbs. lower than the actual dry weight of the camper. Take a look at the tires on the truck. My GM Duramax came with tires rated at 3195 lbs. and that meant a maximum camper weight of 3200 lbs. fully loaded. I quickly sold the tires that came with the truck and bought ones rated for 3750 lbs. to gain 1100 lbs. of load capacity.
You do need to be a smart buyer and take the time to do the research. Don't expect to have everything done for you as this does not work with truck campers or truck camper camping.