The weight of any factory options - 4x4, 8' box, super or crew cab, plus all the lesser ones (tow hooks, ex.) - will reduce payload capacity. What is shown on the sticker is not necessarily accurate and is for a base curb model without any options. For example, upon going to a scale, the payload cap. on our F250 is supposed to be 2701 lbs but is actually 1800 lbs and it's because we have 4WD, 8' box and super cab plus a canopy of about 200 lbs. That's about 900 lbs less than what the sticker on the door pillar says. It is what it is... Many swear that the sticker is 100% accurate tho. and can find themselves in a jamb. If you don't really need 4WD, don't get it. That's the single biggest eater of payload capacity.
The best thing you can do is fill your fuel tank up and go to a scale with just the driver and subtract the weight from the GVWR figure.