Those of us who LIVE in Florida keep telling those of you who VISIT that you are taking a chance. If the LEO is having a bad day you will not only get the fine, but will drop the second trailer on the spot and have to come back for it later. Usually nobody cares, but if you are the "lucky" one, it will ruin your whole afternoon.
Florida double towing law was specifically written to permit commercial trucking operations. Allowed only with a special commercial permit for each tractor; only on certain limited access highways or within specified distance from interchanges (varies by interchange); and NEVER by private users.
I spent several years as Traffic Operations Engineer for Orange County (Orlando and WDW) checking truck terminal permit applications to see if they were within the distance limits from various Turnpike interchanges.
Good luck and be careful out there!
(Florida Statutes Chapter 316; et seq. Available online.)
