“So in other words "I got no answer so I dazzle you with my bull sheet".
Simple question - why is a F150 not capable of towing wihin its ratings?”
Simple answer provided by the manufacturer below. If you can find a TT that will tow well under the specific conditions then yes it can. Good luck.
“Maximum Loaded Trailer Weight
(as shown in the Trailer Towing Selector charts pages 18–32) is the highest possible weight of a fully loaded trailer the vehicle can tow, based on a minimum towing vehicle GVW. It assumes a towing vehicle with any mandatory options, no cargo, tongue load of 10% (conventional trailer) or king pin weight of 15% (5th-wheel trailer), and driver and passenger (150 lbs.). F-Series Super Duty® Chassis Cab models also assume a second-unit body weight based on 80 lbs. per foot cab-to-axle (CA). Weight of additional options, passengers, cargo and hitch must be deducted from this weight”