Cruise ship jobs can be hard to get sometimes. I tried getting an externship back when I was going to school, so did a few others. The response was the same across the board. Either no response at all, or the cruise line informing us that they dont do culinary externships.
Large scale baking is a dying art anyways. All the big hotels I worked at, had around 40 to 70 cooks, and 2 or 3 bakers that just pulled from boxes, and put it on plates. The only place I heard otherwise was the new'ish MGM Grand in Las Vegas. They have a certified master pastry chef there, and I worked with a girl who worked for him. She got to do all kinds of cool sugar sculptures, chocolate rooms, etc. If you want a good learning experience, and volume at the same time, find a 5 diamond hotel, and look up who the chef/pastry chef (if they even have a pastry chef) and research them as well. High profile places, that are very tourist driven are your best bet.