i tow a 27 feets baja(about7000 lbs and 500 lbs on the thong) with a 09 hemi 4x4 3.55 it is just like i have nothing on the back.

 

Towed a 27' Baja from Louisville to Chicago last year to the Loop Cruise that was about 6,000 lbs with the bed of the truck completely full and it did great. I got about 14 MPG with the tow running right at the posted speed limit the whole trip.

My 5,000 lb. boat was towed to Lake Norris twice last year with each trip around 120 miles one way and did fine with fuel mileage a little less due to the much more hilly terrain than the Chicago trip. Our other 24 weekends are all much shorter. It is only one mile to our home ramp from the boat storage and only 20 minutes or so to our other "hot" spots.

I will be towing the 27' again this year from Louisville to Wabasha, MN for the Liquid Jungle Poker Run in August. That is about a 10 hour haul. I will report back after that little pull. I also now have a 39' camper that will likely be around 7500 lbs. that I will put on short trips this year too that I will let everyone know about too.

In all conditions I hardly noticed the boat(s) back there. Even up the hills in Southern KY and Northern TN it easily maintains the 70 speeds on the interstates when others are slowing down. I assure you the power is not a problem regardless of the load.

 

I use to pull around the same wt. with my 04 2wd hemi no problems except at low tide when the angle of the ramp changed and the trailer tires got on to this part due to the low tide, then I would need a person bouncing on the rear and a moving start, the ramp also had cuts in the concrete for traction, they make a bladder bag that you can put in the back of the truck bed and fill with water when you need it. but now have a 4wd and no worries where I go, and tows better than my 04, the 04 was really good too.