I haven’t experienced UK to EU ferry crossings with MH. Having the dog is a pain, we wouldn’t leave him in MH during a crossing. Bea doesn’t do well in boats. True story, one extended trip to Fla, we drove to Key West, booked a hotel where room came with a waterbed, she was seasick!!
I love the boat journey, and a contradiction to Beas sea faring legs. We did the 4+ hour crossing from Oban to Barra, weather was stunning (July) and as we exited Sound of Mull, the Atlantic was flat calm all the way over to Barra. We spent the whole trip over on the seats at the stern, Bea was fine, Two week later, Stornaway to Ullapool return trip, this is a different story!!