Towing an EMPTY tow dolly behind a Fifth Wheel east coast.

I can't tell you if it's legal or not for double/triple towing, but having towed one empty for only a few miles behind my pickup, I surely wouldn't want to do on an Interstate or other main highway, if you've ever seen one being towed empty, you probably wouldn't want to either, it bounced and swayed terribly, the tires were Off the ground as much (or more) than they were on it.