Your truck's rear axle and wheel bearings can handle a load of 10,900 lbs. so the limitation is the leaf springs and the rims and tires all of which can be augmented or changed to get up to a capacity of over 5,000 lbs. of payload. Check your tires for starters. If they are rated at 3195 lb. then the two at the rear will support 6390 minus the weight of the truck at the rear axle. That is roughly 3200 lbs. for most heavy duty trucks. There are 3750 rated tires that will fit on factory rims and if you spend $3500 or thereabouts you can put on Rickman rims and 19.5 tires with a 4400 lb. load capacity.
When you know how much load you can place on the rear of the truck you can subtract the tongue weight of the trailer and know how much total camper weight the truck can handle. Whatever the weight subtract 1000 lbs. to have a dry weight for the camper. For example if the rear supports 7500-3200 or 43000 lbs., and the tongue load is 500 lbs. then the fully loaded camper should weigh no more than 3800 lbs. and you should look for a camper with a dry weight of no more than 2800 lbs.
The 1000 lbs. covers things like an extra battery, AC, luggage rack, food, fluids in the holding tanks, and personal gear. The sticker weight on the camper from the factory will be 200-400 lbs. less than the actual weight of the camper from the dealer or a private party. Easy to verify the true weight at a CAT scale for $10.
Many hard sided campers in the 2000-2800 lb. weight range from which to choose.