Are you able to enter the park late at night?

The park closes at 10. They do give you an emergency code to enter and leave after hours.

We got there late at night and setup camp, had a fire, went to sleep and then the next morning we checked in. They were completely fine with it.

Yes but call the office and make arrangements. They have to give you the code to the gate.

The park is closed at night. Not sure if campers can exit and re-enter at night.