In TN you can pull a double trailer. I don't believe you have to have a CDL, that should be depend on the weight of the towing vehicle, or combined weight of the vehicle and tow. The expedition is another matter entirely. Which engine, what is its maximum tow rating, and how much is all this going to weigh together. "travel trailer" is a very broad description, if it is lightweight pop-up camper, it may be possible, but then again so is communism... I would however, not recommend it. If your family has a gas sipping v6 sedan, u-haul offers trailer hitch installations and hitch rentals.