I think if you stay away from places that offer small menus with hardly any choices and who prepare everything in advance you should be ok. Eating out can be simple if you stick to the following:
Find restaurants that
1. have a salad bar, that way you can pick and choose what you want, including the dressings. Most places like that will supply you with olive oil, lemon juice and/or vinegar if you ask.
2. have a grill for hamburgers, steaks, fish
3. serve vegetables other than baked pototoes and corn
4. are family run restaurants rather than chain because they will be more eager to make substitutions (within reason)
5. serve breakfast all day (in a pinch when nothing else on the menu works a mushroom, bacon, olive, zucchini, green pepper, italian sausage, jalapeno pepper, ham or whatever else you want to throw in omelet is divine).
6. are customer friendly in that they will try and please you as opposed to you pleasing them.

I do not find it difficult to eat in restaurants now that I am familiar with this plan.