That's one great Son-in-Law to let you tow your #6400 dry weight TT with his Tundra! ;)
I'm sure it's towing it just fine, but I'm also sure it's over one or more of it's other weight ratings (either GVWR, GAWR or payload)...
My wife's only driven my new F150 once! ha, ha! :)
Anyway, I saw your posts on the other Ecoboost thread and can only say if you want to tow that kind of weight, get the 3.73 gears at least because you'll need the Max Tow package at the very least if you want any hope of staying under payload, GVWR ratings on the truck..
The Eco will have no problem towing the weight.. It's how much tongue weight you have and how much payload and rear axle weight you have left.
I tow a #5000 GVWR TT (#3400 DRY) and I'm within #400 of the rear axle rating and #600 of the GVWR of my Max Tow F150 with #7700 GVWR and #4050 rear GAWR..
I have a #11,300 "tow rating"... ha, ha!
Anyway, I have the 3.73 gears and get 17 mpg on my daily commute and have gotten 21 mpg on straight hwy runs going 65 mph.
There are many folks that tow 30+ foot, #8000+ lb travel trailers with their NON max tow Ecoboost F150's and are happy... I can certainly feel my #5000, 22' TT behind mine and it's a great tow to be sure... I'll tow it anyplace, anytime..
Can you tow your TT with an Ecoboost? Sure you can... Don't expect any better mpg's doing it than the Tundra, but you should be better mpg with the Eco not towing as long as you stay out of the turbos.. It's pretty hard to NOT enjoy the fun of the power of them, but it'll cost you in mpg's.. :)
Good luck!
Mitch
