Brent,
Since the warehouse is long, and its tracks are long, it implies that it requires the longest cut of cars on the layout. If so, how will a locomotive be able to back a long cut of cars far enough to clear the switch if cars are already sitting on the ferry? Not enough distance between the warehouse switches and the ferry, IMO.
I'm no harbor operations expert, but I would think that the railroad would be greatly discouraged from even being able to back a heavy locomotive onto the ferry at all, even if there were no cars occupying it.