Okay. They can not do anything if you "run out" of something. Guesstimate your nacho chips and cheese from that.
For sides I would get 4 or 5 #10 cans of Bush's beans. Open the next can when you are about half way through the last can. Add your BBQ sauce and some PP to the beans. Sams has some decent potato salad. You can dress it up with some bacon, extra pickles, or nothing at all. The key is not to serve it out of the tubs you buy it in. I like small bags of chips. I would sell them for a dollar so that they run out for sure.
If your food is good, it does not matter how much you make, it will go. If the going is too slow.... samples or more smoke in the air. Both work.