Nitrowarrior is partially correct--the countershaft lubes the trans but it only turns with the input shaft, not the main(output)shaft.
If it is really necessary to tow the car, you could overfill the trans so the mainshaft would be covered with lube and then lower the fluid level on arrival----

But the best method is using an enclosed trailer, and the protection/security you get will make you never, ever look toward open towing again