I looked into it a bit further and it seems that the full tank of fuel and the 150lb driver is accounted for in the GCWR.
"Maximum Loaded Trailer Weight – is the highest possible weight of a
fully loaded trailer the vehicle can tow. It assumes a vehicle with only
mandatory options, no cargo (internal or external), a tongue load of
10–15% (conventional trailer) or king pin weight of 15–25% (fifth wheel
trailer), and driver only (150 lb. [68 kg]). Consult your authorized
dealer (or the RV and Trailer Towing Guide provided by your
authorized dealer) for more detailed information."
2013 F-150 EcoBoost MaxTow
2013 Jay Flight 28BHS Elite
"My wheel lugs require more torque than your Honda makes!"