there are so many ways to do it. from a full stocked setup and food on your location, to just renting the bare cart out. most important. Protect your cart to the max. either put them on your insurance or make them get full insurance up front. Full coverage. everything from loss to total desruction. this is your business, protect it. you can also rent the cart, and sell the food and drinks to them. and if they are not working for you, they also need all thier own permits and licenses too.