Go to the Lance website and download a brochure. It will show dimensions and weights for models that are suited for short bed 3/4 ton SRW trucks and ones that required a long bed and still others that due to their weight need the extra load capacity of 4 tires at the rear axle.
When you get to a 11 foot 4,000 lb. dry weight camper (figure an extra 1,000 lbs. of gear) then the 5,000 lb. load capacity is more easily handled with a DRW truck. An alternative does exist which is to put 19.5 rims and tires on a SRW truck.
The E load range tires have at most a 3750 lbs at 80PSI capacity and most are at 3200 lbs. or less. Subtract the weight of the empty truck on the rear wheels and you have the payload that can be handled. For 2 tires at 3200 that works out to 6400 lbs. minus 3200 for the truck leaving 3200 for the camper when fully loaded. With 19.5 rims and tires the rear wheel load capacity jumps up to 8800 lbs and provides for a payload of over 5,600 lbs. but at a price as the conversion will cost you over $3,000.
With long bed campers the very largest have a dry bath and that is where the weight jumps. Slides also add weight. The Lance 1191 for example has in theory a dry weight of 3500 lbs. but that is before any additions like a second battery, a generator, an AC unit, roof rack, TV, etc.
With a DRW truck you can put anything on it for camping but with a DRW longbed crew cab truck you have something that is going to be a poor daily driver or even work truck. The longer wheel base also makes negotiating turns on forest service roads a lot more difficult and can also make it more difficult to back into camping spaces.
With a camper like the Lance 1050s you have lots of room and a camper weight that even when fully loaded can be carried by a SRW truck.
The rear axles and wheel bearings on current 3/4 and 1-ton trucks have a load rating of more than 10,000 lbs. and this is not the limiting factor. It is the springs and rims and tires and all of these can be changed.
In addition to driving with the DRW truck also consider the ease of loading and unloading the camper. It is doable but not something you will want to do frequently. We offload our camper at a campground and head out with the truck and with a DRW setup I cannot see us doing this.