Will you out run an Eco Boost nope, but it will tow your TT without any issues. I tow a 6800# boat without a problem just order it with the 3.92 gears. As for towing mileage I get around 15-17 mpg @ 70 mph, but again I'm towing a boat not a TT.
Ford has a 3.0 diesel in their f-150 now with a ten speed auto and GM is coming out with a in-line 3.? diesel later this year I think. I have to say I would look hard at the GM if I didn't work for FCA.
I would also wait one year before buying a Ford or GM, IMO you never want to buy the first year of any new engine offering. The 2014 Ecodiesel had a lot of issues that took about a half a year to work out but my 2015 has been a great truck.
Just so you know you can not get the Ecodiesel in a 2019 only a 2018. They are totally re-working it for the MY 2019, new heads, turbo and higher HP/TQ. The trans is going to be the new GEN II eight speed also.
Don