I have to agree with Campfire Tom. You’re likely looking at the 9-11mpg area and I think you’ll be happier towing a lighter TT. But that won’t do a lot for your mileage, air resistance is the culprit. Or another option is to spring for a bigger TV. Where you live I think you’ll be doing a good amount of mountain driving and pulling anywhere near your max may not be a lot of fun. Meaning slow, high rpm climbs up every grade. That is probably acceptable if you’re mostly in the flats and grades aren’t common, but it can get pretty tedious if you do a lot of climbing.