I use my Mirage for business purposes and tow with it about 8 miles each way, every day. It's a small concession cart that only weighs about 200 pounds fully loaded, but it does fine. I keep it under 60, stay in the right lane, and really try to not stress the powertrain. It's hurts gas mileage by about 20%, almost exclusively because of the aero drag.
I've got a job this weekend, three hours drive each way, with 1400 hot dogs and buns in the car. Haven't figured out how I'm going to do that, yet.