Have you tried churches in the area? Some might rent out rooms even if you're not a member and then there might be kitchen access as well.
What about a restaurant, most managers are pretty open to guaranteed business and our experiences have been that most people are ok with paying for their own food. We've done Freso's on 377 in Watauga, Mi Pueblo in NRH, On the Border in Fossil Creek. Otherwise do it as an open house at someone's house if you don't think you're going to be able to fit everyone in sometimes people are happier with that since they don't have to commit to several hours on a weekend with a busy family.