An Update on Cruising While Keto

I'm currently on Day 4 of a nine day cruise with Royal Caribbean. This is a normal cruise and not a special "keto" cruise. I have been on several cruises in the past, but they were all pre-keto and very carb laden. I never turned down desert or bread previously. Now I'm looking at the dining options through a new lens, with low-carb high-fat eating as the goal. I'm also still practicing time restricted eating, eating only lunch and dinner. I did a 3 day fast on prior to leaving including one day of airline travel. My intent is not to fast again until after the vacation. The last couple of days I've been struggling. I haven't intentionally eaten anything that isn't keto approved. But I think there must be some hidden carbs. For example, one of my go to meals when I'm dining out is a burger with mayonnaise. This gives me a low carb option with some extra fat. However they used Heinz mayonnaise on the ship. The third ingredient is corn