J., I'm so sorry you are going through this. How compliant is he with you at home?
If he listens to you at home and does what you say without the drama you are detailing here, then the issue is that he doesn't recognize authority outside of you. You mention that he misbehaves at home. How much misbehavior are you meaning? What do you consider "typical stuff"? If you are not strict with him at home, between that and not accepting authority from another adult, then this will be a real problem for him when he goes to real school.
I would ask my ped to help me find some resources for how to change your pattern of discipline at home so that you can help him learn to behave better. Without that, you'll just keep having failures outside of home like at camp. Once you've put a new discipline routine into place and he's finally accepting it, enroll him in preschool. There he will learn to work within a group and accept his teachers' authority. It will serve both of you well for when kindergarten comes around.
If you don't change anything at home, J., putting him into preschool will possibly not work out, and they will ask you to withdraw him from the school. They do not have to put up with a child doing what your son is doing in the classroom, and they won't. Public school does have to, to a certain extent, but it will cost your son so much in lost time learning and cause you much grief and time conferencing with the school over his poor behavioral skills.