I was in touch with Ludwig, Captain of the Stalratte (Steel Rat) which plies the waters from Panama to Colombia through San Blas Islands, etc. He did a trip to Cuba/Jamaica in November with at least one biker on board. He plans to do another trip in April much the same itinerary. Trouble is he sails from Panama/Colombia so you have to be planning to ride down that far or already be down there, below or above the canal.
I am trying to persuade Ludwig to do a more biker-focused tour preferably starting from, say, Mexico and more of a freighter for biker customers (though he could mix this with other regular passengers happy to stay on the boat). I myself would get off the boat and ride around Cuba for at least 3 weeks or a month preferably finding my own lodgings, etc. and then get on the boat again when it is headed back. He spent a week or so in Jamaica as well last time, but Jamaica pales in comparison to Cuba. I have been to Cuba many times including a couple bicycle trips and it is ideal for motorcycling, preferably a dual purpose but even a cruiser would work if you dodge the pot-holes.
Any interest out there? Enough of us could probably motivate Ludwig to do something for us for a reasonable fee. Sign up now for next November, hopefully out of Mexico's Yucatan.

Cheers
Larry