How short as in height could you go with a gooseneck before it would be a problem as in hiting the tow rigs bed if it was only used on flatbed rigs? Fifth wheel trucks dont have alot of room between the top of the tail of the frame and the frame of the trailer but they for the most part dont cross as many ditches.
not a flat bed but i have touched the bed corners on my truck. i have about 12" of clearance on my truck. this wasn't exactly balanced to well but i was driving a short distance