I've shipped several boats, 6 to 13 ton (33 to 38ft) and the hauler always
preferred and recommended that the mast (or dingy) be transported on the
trailer. They just don't like anything on deck and the trailer is easier to
monitor..

The owner is always responsible for securing all gear remaining mounted or
in the interior. I learned from others, much like yourself, the all gear
inside needs to be lashed and secured for the worst of conditions. There is
a lot of vibration and severe motion when these haulers are doing highway
speeds (or more) and braking for stops and turns.

I always shutter when I see a boat owner transporting any outboard motor on
a bracket, even on his own trailer. Hell of a strain on the hardware or the
transom. All it takes is a speed bump to break something, not to mention a
cross country trip.

Sorry I don't have much simpathy and hope you learn from this experience.


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions