If you are contemplating outdoor boot-camp style classes, be sure to check in with the owner of the park/space you plan to use. Some cities and counties require you to file for a permit (which may or may not have an associated fee), and some prohibit the use of their spaces for group training.
Have you looked into what other non-fitness spaces exist in your area? Churches often have community rooms that might be useful for you (the church where I grew up, for example, rented the room to Jazzercise). Fraternal organizations such as the Masons, Elks, Eagles, Oddfellows may also have a large room that could serve your purposes. Don’t forget to look into the VFW and other military organizations as well, they often own property that has indoor and outdoor space.
Your creativity will help you meet this challenge. Make a list of what you need in a space (e.g. access to restrooms, non-carpeted floor, etc.) and then let everyone you know you’re looking for such a space. You might be surprised where you find it–there is an art gallery here that has Zumba classes!