I/we have a 2003 Expedition and tow have towed our 25' Classic many miles.....no problems with one exception....had to buy a new transmission (was an overhaul but seemed to have replaced a lot of things) but that is my/our fault. I think that it (transmission) got hot going over a pass not recommended for trailers in CA.
The Expedition we have does not have the 3-valves or the six-speed transmission. As I wrote, it does well for us. We only have a Reese hitch set-up with the bars and yet there is no sway that the Expedition does not settle down
Tow vehicle is "the boss".
Originally, we were planning to tow with our 2000 Jeep GC BUT had to do "crazy Ivans" to see behind and the trailer was really in control.
You are also better off than we as you have the extra length of the tow vehicle... EL
Do not worry, get a good sway control hitch, and enjoy. I do not think a Hensley is a necessity