I got lucky and found my brand new Max Tow F150 sitting in the back lot with the USED trucks and got it for $10k under sticker... :)

I like the 3.73's with the factory 20" wheels.. It runs in 6th gear most of the time on the hwy towing my #5000 TT. Not towing, it gets me anywhere between 21 and 23 mpg going 60-65 mph. Going 70 mph, it's running around 1800 rpms.
I've not taken it on a road trip where the speed limit is 70 while not towing, so not sure how it'll do at that speed? Towing I get around 10-11 mpg.
The pull the Eco has with the 3.73's is really strong.. I love it! :)
Good luck with the search!
Mitch