don't have a dolly, but can relate to unhooking my utility trailer with a load on it
if the load is in front of the wheels ti's usually ok and the front wheeled jack will hold it up, BUT if the weight is behind the wheels the trailer will basically STAND UP with nothing to hold down the front end - not good or the tow vehicle or anyone standing close - damage WILL occur
so on the tow dolly, I would have the same concerns-
unbalanced weight on the tow dolly and when unhooked the front of the dolly flies UP (or down) making it impossible to rehook
(and probably impossible to get the toad off the dolly?!?)
even ANOTHER reason why I'm glad I tow 4 down !