First, welcome to the Forum!
As several have said, most published weights from the manufacturer are publicity fodder. Ignore them all!
Published max tow capacity uses the lightest base truck with max towing package, two 150# passengers, very lightly optioned, and a full tank of fuel. No more passengers, no cargo. The published Payload is for the same truck with no passengers or cargo. Some charts will be specific for the body, wheelbase and power train, but the payload is for a base truck with no options. The footnote says the weight of all factory and aftermarket options must be subtracted from this payload value.
The real payload for YOUR truck is on a yellow label on the driver door B pillar which states the max load of all passengers and cargo shall not exceed XXXX. This is the real payload as the truck left the factory.
Add together the weight of all passengers, pets, car seats, tools, firewood and other cargo to be carried in the truck when you go camping. Add 80# for a WD hitch. Subtract this from your payload. What is left is the max hitch wt your truck can handle. Remember, hitch wt plus WD hitch plus passengers and cargo can not exceed payload.
A TT needs a minimum of 10% of its' gross weight as hitch wt to give good towing manners. Take this hitch wt X 10 to get the max weight of TT you can tow. Note, this is the LOADED trailer wt, not dry wt. Use the TT GVWR here.
The engine, tow packages, rear end ratio, etc also come into play. Trailer Life magazine provides good information on max tow ratings based on these factors, but remember this is for a truck with no cargo.
Hope this helps.