Do your research in the region you want to operate in. What kind of prices do hot dog carts and/or food carts charge for events and what is the volume of business? How many days a week can you book an event or somewhere to set up with foot traffic? There's definitely opportunities everywhere to sell food to people conveniently. Every microbrewery without their own food service basically has a food truck or two outside on the weekends. A large neighborhood near me does a food truck night during the week in the summer. Corporate centers where they have people working in the office tend to be good spots for selling lunch foods.