Yeah, thats a good thought too.
My truck has a tow package. Tranny coolers are pretty easy to install Weaz, should be able to tie it in right in front of your radiator.
Gas mileage, yeah that'll drop through the floor.
I get 18 on the highway with my truck, towing the trailer it goes down to around 10.
Hope we havent talked you out of anything yet Weaz, just getting you some info