The largest Airstream that I would buy is the 27' Flying Cloud. It's GVW is 7,600 lbs., allowing for 1,732 lbs. of load because the unit base weight with the LP tanks full is 5,503 lbs. That allows for more weight than I can imagine carrying in the trailer, but I use the 7,600 lbs. for calculation.
The F150 w/ 2.7L Ecoboost minimum base curb weight is 4,371 lbs. while its allowed GCW is 13,100 lbs. The combination of the vehicle and trailer is 11,971 lbs., which allows a margin of 1,129 lbs. That margin would cover me, perhaps a generator, a one person kayak and whatever.
The hitch load would be 791 lbs.
Of course, I have to stay within limits for the sake of the warranty and safety. Therefore, I am concerned about whether the margin is adequate.