@fritz3000g ,
As a car and truck fanatic, I can tell you that what you end up saving in mileage with a turbocharged Eco Boost will be spent on the premium fuel you've gotta refill your large tank with. I have a several friends who drive Eco Boost F-150s, and they spend around $85 a week on refills...that's down here in Texas where prices are lower! You're going to want a towing vehicle that can tow at least a thousand pounds more than how much your boat weighs so that you're not putting as much stress on the engine and transmission. The only vehicle I can think of with that kind of towing capacity would be a truck, either powered by gasoline or diesel. Diesel trucks offer an amazing amount of torque for towing, decent mileage, and are solid as a rock (as long as they don't say "Dodge" on them). They can be expensive to maintain, though, and are also often available with turbo options.
Here's another thing. I can almost guarantee that a used towing vehicle will either have a ton of miles on it, or be worn out due to all the towing it's already been used for. A lot of people also tend to overprice their towing vehicles, especially trucks, because they think what they have is "special". A good place to look would be on a certified used car dealer website, such as Car Gurus, CarFax, etc., and NOT Craigslist, Ebay or LetGo. The latter sites are ridden with fraudulent scammers and criminals who could lure you into either losing thousands of dollars, or to their own property (this happened to a friend of mine just last week). In a nutshell, it's going to be really difficult to find a towing vehicle for a price lower than 25K, and that has less than 100,000 miles on the odometer. A lot of the other comments here on this forum are filled with really good stuff. In my honest opinion, as long as you don't buy anything built by Chrysler and has an engine larger than 5 liters, you're in the clear for a good vehicle!