We used to drive all over the place in our VW, not the same sort of thing as you are getting as its more like a van with beds and a cooker, when we drove up to Dundee from Market Harborough with our then dog, Bruce a Rottweiler cross, he refused to sit down at all....he stood with his feet on the back seat looking out the window both ways and when we were at our wedding venue accommodation, student halls in Dundee, he never slept much either, when we got home I thought he was ill as he hardly left his bed.......he was like that for 2 days but then back to his normal self!! A secured big crate would be helpful, that way the dog would not get thrown around and would be more able to relax and remain safe, nice fluffy covers and regular stops but no idea of the ferry, 12 hours is a long stint..