As part of your argument, I'd include the idea of spending local money locally. The restaurants in your town should be offended by this policy.

My first go-to would be boosters/parents. They could raise money or simply cook/provide the meals themselves.

We have a local church who provided our meals on home games several times.

You might get Lions Club or other civic minded organizations to help you.

Put the word out in public cold-call on Facebook or something. We have an empty nest couple in town who simply likes feeding kids. They totally volunteered to care of meals more than once.

You might get a local restaurant to donate meals but if I owned a restaurant in your town and knew I'd NEVER get any business from you, I doubt I'd help you.