Research your facts before calling me wrong.
HDPP is the option set which get the F-150 the maximum payload - almost 3,300lbs; it starts with thicker frame rail, adds 9.75" differential & heavy springs. It is NOT to be confused with the Max Tow Package. The payload on the Max Tow is almost 1,000 lbs less than the Max payload truck. In both cases, it will be a 4x2 XL single cab, long box truck.
Under j2807, the truck is required to be loaded to max rear GAWR and GVWR. Trucks with lower GVWR and same GCWR tow more. We train our engineers to be good at getting the best results they can on tests.
Big sore spot with F-150 owners: there is too little payload in the Max Tow package to actually tow big trailers in anything other than the SAE test (Drivers & passengers average more than 150lbs, options on truck, tongue weight of >10% trailer all reduce limit). HDPP packages trailer towing rating is ~1,000lb lower due to the higher GVWR, but it can actually hit its towing limit.
I know exactly what I am talking about and I know the difference in the 2 packages and you said the same thing I said, only worded differently.
The best payload and max tow at the same time is with the XL regular cab longbed 2wd with as few options/accessories as possible and the 3.5 ecoboost.
You can only tow 13000 pounds if your payload can handle the tongue weight !
That is fact regardless of if it annoys you !