Don't you have to minus the net weight of the vehicle with accessories, passengers, fuel and cargo from the GVWR before you have the payload number? Or did I misunderstand what GVWR stands for.
I'm assuming that Ford has already done all that before publishing the payload and GVWR on their website.
Also, logically we have to assume that Ford isn't going to sell a non-compliant accessory to the public. That's mad negligence LOL