I deal with commercial laws every day so just to be sure my answer was correct I ask my safety man about your question. This is what he said..........
Commercial doubles are allowed in all 48 states and follow the rules I stated below. RV's and other private vehicles have separate rules because they are exempt from things like CDL's and there is no way to enforce if the driver is qualified to drive such rigs. So the federal rules do not apply. He give me the link below with the non-commercial rules. You can see that non-commercial doubles are not allowed in Florida.
From the Florida Department of Highway Safety and Motor Vehicles web site.......
"Florida statutes require that non commercial vehicle combinations consist of no more than two units and such combinations may not exceed a total length of 65 feet. F.S. 316.515(3)"
Same-Day Shipping! Most of our stocked parts ship the same day you order (M-F). Expedited shipping available, just call! Most prices for parts and manuals are below our competitors. Compare our super low shipping rates! We have the parts you need to repair your tractor. We are a Company you can trust and have generous return policies! Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ More Info ]
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.