They did one as a fundraiser at my sons' school last fall. I believe the food trucks were Big Star, Saucy Porka and Wagyu Wagon. Was a pay-for-a-ticket in advance, all-you-can eat type of thing. The trucks parked on the playground but they brought food in batches into the gym/auditorium and set it up on tables in there. Believe there were approx. 300 people there and did not seem to be an issue with running out of food. I do think the format of setting up the food on tables (there were just individual, single-serve plates/paper baskets of things) probably helps a bit with the mayhem/delays/frustration that can come from queuing up single file at a food truck window. Not sure how the Chicago Food Truck Festival worked, but I think selling tickets in advance also probably helped the food truck folks with planning for how much food.
Was not involved in organizing, so unfortunately cannot give you much more info than the above, but was very well-organized and without any issues (unless there were things behind the scenes I did not see). May be worth giving some of the trucks/establishments above a call and see what they can do and for what price, what types of info they would need in advance, how others have organized events they have participated in, etc.