We were looking at the same problem. We were looking for a land based vacation because of the age of our children. We thought we would just get ourselves to Anegada and chill, but moving that many people, children and seniors through all of the ferry hassles just didn't seem worth it. We Contacted Fred Rebarber at Air America. We had eight people going so it seemed reasonable for the flight from San Juan to Anegada.
Not sure of your circumstances, but I'd rather pay up a bit and get where I'm going than to have to get a hotel room, unpack, repack, and still deal with ferries.
Just a thought
Good luck