Your commuting is far greater than your towing needs, so its going to be tough to justify the low fuel economy everyday for any vehicle capable of towing 6500 lbs. You may want to consider both an economical commuting car and a cheap older vehicle strictly for utility & towing, as I did. My commute is 108 mi. roundtrip in MD, and I do that with a subaru outback, but there's no way I'm going to tow with that, so I got an older cheap v-8 pickup just for tow (and dump, lumberyard, etc) duty. Good thing too as it only gets 11-12 mpg, 9-10 when towing.
The smallest, most fuel efficient vehicle I can think of that is rated to tow 6500 max would be the Chevy Trailblazer or GMC Envoy (possibly also its Saab version, the 9-7X which is being heavily discounted, but is a Trailblazer under the skin). I've used these for work and exceeded 20mpg (barely). Read all the reviews here at Edmunds - some people hate the seats. I don't know of any V-6 that is rated that high for towing. The Chevy Tahoe-GMC Yukon would be better tow vehicles with a max rating of 7700 lbs, but with correspondingly lower fuel economy. For towing, you'd want the 5.3 liter v-8, 3.73 rear and limited slip. The auto 4WD would work for winter driving and they have decent ground clearance for driving over snow.
If your total towed weight was say, 5000 lbs, that would open up more vehicles - and more fuel efficient ones. Despite its lousy rear visibility, I like the Toyota FJ Cruiser, but its max towing with its 4.0 v-6 is only 5000. Add up all your components - hull, motor, trailer, full tank of fuel (figure 8 lbs/gal), tackle, options, anchor, coolers with ice, etc. and see where you wind up.