Lunch ideas?

This is my story: I work at a day camp in the summer, and it supplies food for all the campers and staff. I've been there for 13 years, and while the food is certainly tasty, I've always managed to gain weight in spite of the sweating and sports and hilly terrain. We're not really supposed to bring outside food with us unless its because of allergies, but I'm considering my weight loss goal a dietary restriction, and I don't really care.

We have access to a salad bar every day, and I've already decided to bring my own low-fat dressing and a 1/4 cup measuring cup to use instead of the spoon, so I know exactly what I'm putting on. The problem is that I'm hypoglycemic, and know I'm going to need a bit more than a salad in the heat we're expecting! I also don't love cold food. Does anyone have any ideas for quick, easy lunches that I could throw in a thermos or something? It needs to be unobtrusive and not require too much assembly to eat (the second my campers see it, they're all going to want to bring their own lunches too!). An occasional sandwich is okay too. Oh, we're also a nut-free camp, so nothing like that either. Thanks, everyone! I'm so stumped, and nervous that this is going to screw up all my hard work!