I have an 8000 lb 30-foot Airstream that is very aerodynamic and sits low behind my truck to where its almost invisible from in front of the truck. I get about 12 mpg when towing it with my F250 Diesel on relatively flat roads (most of TX). I towed my son's 3800 lb ultra-light 23 ft. trailer that is VERY square, especially in front, and sits very high behind the truck... I didn't get a good read on MPG, but the mileage seemed worse at highway speeds when wind resistance mounts exponentially. So, I don't think weight matters as much as resistance at highway speeds. The front of the boat with the shrink wrap over the front bimini is a giant air brake, and the faster you go, the worse it gets. It'll get a lot better when you don't have the shrink wrap. Cool thread! I'm enjoying watching it! In my youth, long since past, I was a speeding-ticket magnet. That started to change when I got my first boat (an 18-foot Hobie Magnum catamaran) and I was forced to go slower. Now, the older I get, the slower I go!