It really depends on your dog. I think they allow pretty ample time, although it’s obviously not ideal for a dog.That would be fantastic! I'm expecting to depart in about a month or so. I had heard that the ferry route is very scenic but doing that with a dog might not be recommended since you might not be allow to visit your dog often.
I have a large German Shepherd that is very skiddish even though he’s around other dogs all the time, and he’s done fine on the ferry. You get about 15 minutes to take them out of the car and walk them on the car deck, from what I remember around 5-6 times a day. They do it in certain hour intervals so sometimes it’s at 3 am which you may not like.
The ferry is very pretty and enjoyable of a ride. Tons of people do it with dogs, so I wouldn’t let that deter you.