Newer transmissions tend to have lubrication pumps. The older/crude transmissions used a splash gear to sling oil. Towing a newer vehicle can cause damage due to lack of fluid circulation.
Also, pay CLOSE attention to those vehicles that can be flat towed. MOST have limitations on speed, and distance. Very common to see "under 50 MPH, and no further than 50 miles".
There is another option. Check with Remco Industries. They've been around a LONG time, and offer solutions for many vehicles. They can add driveshaft or CV joint disconnect, or an auxiliary transmission fluid pump. Obviously the pump would be a much cheaper/easier option.
No affiliation with them, but I've looked into their services before buying the Jeep.
http://www.remcotowing.com/Towing/Store.phpWhat's unique about the Jeep is it has a true transfer case. To tow the vehicle, the transfer case is put in neutral, and the A/T in park. No miles are recorded on the odometer. I do have to leave (an unchipped) key in the ignition to unlock the steering - newer models don't have a locking column.
Good luck!