I like the tow mode in my 2017 Expedition XLT EL. Shifts nicely, stays in gears longer but not obnoxiously long and down shifts nicely when slowing down. It has heavy duty tow package. While towing our 7,000+lb travel trailer. I average 8.5-10mpgs usually driving 70-75mph.
My first two times towing our trailer was a nightmare. So much trailer sway. It was impossible to maintain 55 - 60mph. I then realized the dealer provided me the wrong weight distribution hitch. Dealer gave me the one I originally asked for and the trailer was much better but not perfect. I made a few adjustments to the hitch along with 10 ply tires on my truck and all is fantastic now.
Not long ago I saw a nicely equipped new Ford Ranger towing a two axle travel trailer that looked like it was in the 6000+lb range. I was a bit surprised.