I know you're not exactly on Atkins, but that's been one of the cool things about it to me. I've been in restaurants in three states since starting, now, and when I have to do some substituting, the waitress either asks whether I'm on low-carb, or says "Sure" when I ask whether she knows about Atkins. They always have worked with me, it's always been no-prob.
Dan
Often when the waitress asks me what kind of potato I want, I ask for a sliced tomato instead. That works well for both of us.