ib516, I've enjoyed your posts on the 6.4--don't stop.
The fisherman comment was priceless. I had to think about it for a moment before I got it.
As far as mileage, once I timed it just right, and got 99 mpg towing the trailer, down I-90 off Lookout Pass, for 5.5 miles. When we got home, we averaged 8.5 for the trip.
Each rig is going to tow differently then the next. Our trailer sits pretty high behind the truck and I'm sure the wind beats it pretty badly due to wind flow off the camper shell.