If that is what the sticker says in my experience realistic payload is 100lbs or so below that.
My biggest culprits are;
spray in bedliner
rubber mat in bed
Jumper cables and other misc stuff under the seat.
We went out for a few trips with our old half ton and I usually drove then one trip out my wife drove home and it was pretty windy. She got tired arms and decided we needed a new truck after that!