I have a business license and am allowed to use my local parks.
Every city has it’s own policies, I suggest finding out the requirements prior to starting your bootcamp as it would be really humiliating to be asked to leave in the middle of a workout.!
Liability Insurance for outside training is a good idea along with waivers that are detailed towards outdoor training, as there are episodes that can occur that you may not be aware of such as uneven pavement obstacles in your way that a bootcamper can trip over.
We use a small park and are very respectful of the neighbors and others using it.