I couldn't add the attachment when I tried to edit. This shows what each package has.
Unless something has changed, you CAN order max tow and HDPP, but the 3.73 gear actually carries a lesser gcvwr than the 3.55 non HDPP truck. In the Ford forums we speculate that it is due to the combo never being recertified for a greater load with the wheel/tire setup that comes on HDPP vs the ones max tow comes with.