I suffer too, S-D, the slightest swell is enough. Old Sea Dog called Mr J2 strolls about casually and eats and drinks things. I get a seat in as near the middle of the ship as I can get, on a low deck, and I stay there as much as possible. Pills make me feel so very ill that it is worse than the seasickness and I wouldn't trust myself to drive for a couple of days after I've taken one.
A standard bunk might be a bit tight - if you go for one bear the aforementioned advice in mind and do not be pushed onto the upper bunk no matter what the whining! My personal advice would be to book a sleeper chair - reclines, is comfy, leg space etc., bring your own travel-rug & pillow if I recall rightly. They turn the lights right down and it is a separate area. I don't sleep well but I do doze (OH, of course, sleeps like the dead). Depends how far you have to travel the next day really.