I bought a 2008 Four Winns SL262 from a dealer in Islip, NY. We live in Cincinnati, OH. The dry weight for the boat and trailer is about 7500 lbs. 5500 lbs for the boat and 2000 lbs for the trailer. 75 gallons of gas (give or take) is just under 500 lbs. So all total, almost 8000 lbs, 12 hours one way.
I used my 2014 Ram 1500, 5.7/8hp70, 3.21 gears. For the vast majority of the trip, I was traveling around 80mph without an issue. I installed the Timber Grove airbags in the rear prior to the trip, which improved towing performance ten fold.
I tow this boat every weekend down to our campground (40 min one way) and back up. The hill we have to go up and down on is fairly steep, I don't know what incline percentage is. I'm extremely surprised at the capability of this little half ton, but most definitely need a diesel very soon. I've developed a whine at speed which is not a wheel bearing or anything obvious, but still concerning, and likely due to what I'm pulling and the speed at which I'm pulling. None of my temps ever got out of control, trans 195 at its highest, oil around 240 and coolant hit 230 a few times, but nothing I'd say is bad for some of the inclines we had to deal with coming from NY.