The tow dolly that I'm looking at is the
Acme EZE Tow. It has hydraulic surge disc brakes, so braking is not an issue. It also has the emergency breakaway system (which is now required in many states.) So the dolly is completely self-contained. I would not need to alter my truck at all.
I would get some kind of a portable light setup for the back of the truck, although the brake lights on the dolly are clearly visible from the rear.
I'm assuming that if I put the tranny in neutral, the truck will tow fine. The rear end and driveshaft would be moving, but the tranny wouldn't be, except for the output shaft.
The problem I have is I can't find a trailer, even an aluminum one, that keeps my total weight under 4500 lbs. My GCWR is 9321. My car weighs about 4800 lbs. Max trailer weight is 4500. My truck weighs 3400. The lightest trailer I've found is 1400 lbs, and that doesn't include the weight of the hitch. So towing the truck on a trailer is out of the question, using my Flex. Using the tow dolly, my total combined weight would be less than 3800. That's well within the range I'm allowed. That's why I'm considering the tow dolly.