I want to be clear that I DO NOT intend to use a hitch extension to get a little extra drawbar length, allowing me to drop my tailgate with the trailer attached. In the photo, I just put on the one I already had to see how much length I needed and what it would look like. 
The idea of extending the tongue of the trailer instead of the drawbar would be good one since this is a permanent need but, I don't want to do that to a brand new Airstream with no recourse to go back. So, I am going to try rotating the electric jack 45 degrees to get the head out of the way and use a slightly longer drawbar, 12 - 14 inches. 
The 3800 lb trailer WITHOUT the extended drawbar performed extraordinarily well on a recent 1,000 mile trip, without a weight distributing hitch. It is a beefed up F150 with the heavy duty load package and the tow package. The tow package does have sway control that seems to be managing that end of things well. I also have a good deal of cushion in tongue weight and pulling capacity. I realize that if I do decide to go to a WD hitch I probably can't use the longer drawbar. 
The trailer folks and the Airstream folks are both OK with this and, if there are any surprise handling problems, I can always go back. The longer drawbar is out of stock and due in Monday. I will keep you posted. 
Holler if you can come up with anything I have not thought of.