I have over 4,000 miles flat towing on my 1991 Sammy. The previous owner had over 100,000. It has never seen a tow dolly, or has it had the rear driveling disconnected.
I suggest you consider getting a tow bar, and flat tow. As I recall, do not disconnect the drivelines, transfer in neutral, tranny in second, about every 250 miles start and run the engine for a few minutes. I never run the engine. I think these are the instructions on the transmission tunnel.
Wayne