Motor Vehicle, Mobile Home, Off- Highway or Vessel Description. Year. Registering a trailer in Florida requires a Florida trailer bill of sale form.A completed form to title and register a trailer is required. The bill of sale must list the Trailer Identification Number or the trailer's license plate number. If you have purchased a used trailer under 2,000 lbs. Owners of used trailers weighing over 2,000 pounds must submit a bill of sale, including the trailer's year, make, identification number, and previous state.