Check out
Maine Cat - they have 30 and 41' cats for charter in Hopetown, Bahamas. Not exactly what you are looking for in terms of the length of the
cruise, but they might make you a deal.
One other point besides the
hurricane season is you might want to just fly to the Bahamas instead of having to make two crossings of the
Gulf Stream. That way you can spend more time enjoying the trip and not worrying about crossing what can be a nasty piece of
water.