interesting question.
I looked into buying one of these Tow hitch dollies for occasional recovery

they are available on ebay and elsewhere for around £75 which is quite reasonable .
The thing I particularly like about them is they fit any tow hitch and fit in your boot and take minutes to fit to the hitch but I couldn't see how you could make certain that the scoot wouldn't fall into gear during towing.
Its just occured to me that it should be perfectly feasable to tow a scoot by the rear wheel and lash the handlebars to keep the steering and front wheel straight. That way you could tow for a thousand miles without any risk to the gearbox .
The worse that could happen is the tyre might burst due to heat from the excess weight .You would probably want to remove the speedo drive cable to the wheel though
Dayum

I just built an expensive scooter rack ....