First of all that was an FJ55 being towed behind an 80 series truck which is not at all what he is asking. I have towed vehicles on tow dollies and open trailers for thousands of miles and had no incidents other than flat tires.
The most important part of towing anything is that the tow vehicle has to be large enough to control what is being towed. A 4 thousand pound 55 on a thousand pound trailer with another thousand pounds of cargo is clearly over the safe towing capacity of a 5 thousand pound truck.
However a 100 series land cruiser is more than capable of towing a 3k pound 40 on a dolly. The quality of U-Haul equipment is an entirely different argument all together.