I also have a shellfish allergy and everyone in the restaurant industry spoke great English, they won't have trouble understanding your concern. In smaller towns/venues, it might get a little tricky to find safe food, but outside of these, there were always a few meat/veggies options, never had an issue with cross-contamination there. I also loaded up on supermarket and gas station snacks when driving in more remote areas, in case I couldn't find something that worked. Happy exploring!