I usually do burgers (or a chicken sandwich) with no bun (just toss it.)
They have the turkey legs, right? I have never had one, but perhaps that is a good snack option? (If the outside is covered in a sauce, just pick off the skin.)
Salads are a good bet, but watch for hidden sugars in the dressings (even the creamy ones at say McDonalds are pretty high in sugar, especially if you are induction.) Same with ketchup on the burgers (mayo & mustard are OK.)
If you aren't in induction (or if you don't mind the few extra carbs, bring some small helpings of almonds or other nut for a snack.)
Finally, I always bring a water bottle with me & fill up at the drinking fountains (I am not a picky water person, and prefer it a bit warm anyway...or at least not ice cold!)
Best of luck with Atkins! I did it for a few years before getting pregnant, and am slowly starting back on it (still nursing.) The first 3 days can be really rough, but hang in there...you will eventually start to feel great! While eating this way, I don't get the "afternoon snoozies" I used to get.