There's been a lot of discussion as to the legalities of towing with or without brakes. However there are standards and recommendations by the manufacturers that are just as important. In the case of Ford trucks the manufacturer makes the following statement:
"The braking system of the tow vehicle is rated for operation at the
GVWR not GCWR".
This is similar to the statement the make in the F53 chassis manual. The only difference being that in the F53 manual they also say anything weighing over 1,500 lbs. requires an auxiliary braking system. They don't get into the legalities or semantics of what constitutes a trailer. They simply say ANYTHING weighing over 1,500 lbs. requires brakes