The payload sticker is an estimated amount of the max additional payload you can haul if nothing is in the truck but a skinny driver. But nobody tows with an empty truck, so the manufacturer's payload number is not very useful.
To determine your actual unused payload available for hitch weight, load the truck with everything that will be in it when towing, go to a truck scale and fill up with gas, then weigh the wet and loaded truck with you and your passengers in it. Subtract the weight of the wet and loaded truck from the GVWR of the truck. That's your actual net payload number you can rely on.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 EcoBoost SuperCrew.