I would like to see your door sticker. That is the real number after subtracting all your options. Aftermarket air bags add nothing to the legal payload capacity. Here is my sticker on an 2011 f150 ecoboost supercrew 2wd.
View attachment 350676
GVWR sticker. What jumps out at you about this one, in comparison to your Ford.

Payload Sticker
