I agree that a properly equipped half ton truck CAN tow a travel trailer fully loaded at 7k or less. Any more than that and you may be in 3/4 ton truck payload territory. Beware of payload issues with 3/4 ton trucks with diesel engines. The diesel engine is very heavy and eats up a lot of the the payload.
My 24' toy hauler weighs 6640 to 7240, with a hitch weight of 780 to 1000, depending on how it's loaded. The cargo and occupants in the truck weighed 347 to 707, again depending on how it's loaded.
The truck is loaded at 94% to 97% of its maximum rated weight. The 3.5L turbocharged Ecoboost engine is quite sufficient to tow the weight, but the chassis is nearly completely loaded to its maximum rating.
Educate yourself on the definitions of some terms and how they affect a tow vehicle's capability:
GVWR: Gross Vehicle Weight Rating
GAWR: Gross Axle Weight Rating
GCWR: Gross Combined Weight Rating
Payload: Maximum weight of occupants and cargo, Payload = GVWR - curb wt.
Tongue weight: The portion of a trailer's total weight that is applied to the hitch ball
Hitch weight: The sum of the weights of the trailer tongue and the weight distribution hitch that is applied to the hitch receiver on the truck.
This reflects the data from four times across the scales on four different trips:
Find this sticker on the driver's door of the truck you are considering. It shows the GVWR, GAWR and Payload.
Find this sticker underneath the hitch receiver of the truck you are considering. It shows the maximum hitch weight you should apply to the hitch receiver.
And it's not just engines and springs. A 3/4 ton or 1 ton truck will come with a full floating rear axle instead of the semi floating of the half ton truck. Bigger brakes, too.
Don't expect any truck or camper salesperson to have your best interest or safety at heart during the sales process. Also don't expect them to know anything about matching the requirements of the trailer and truck. That will all be on you. The sales person will tell you that your truck will pull any camper he has for sale or that your camper can be pulled by the truck he has for sale, "no problem".