I can tell you that my parents, who keep kosher in and out of the house, are a LOT more flexible when they are travelling places without kosher restaurants.

Usually we''ll do Italian or fish. At a breakfast place they might do waffles since they're not cooked on the griddle with the bacon and sausage. Fish usually broiled, since the flame will kind of obliterate the shrimp that was on there previously. For Italian think lots of cheese ravioli in basic marinara sauce.

More observant folks may stick to things like only fruit or veg. Possibly only what they peel themselves.