I would have very kindly have asked her "Are you completely ignorant of the rules here or do you just think they don't apply to you?" When she then would have went into her "I've been camping here for 40 years......" rant, I would have smiled and nodded until she gave me a place to break in and then said "You know, my Dad told me never to argue with stupid people because they will wear you down and beat you with experience. You clearly are more experienced than I so I'm going to end this discussion."
Then I would have walked over to my campfire and sat down and drank a cold drink laughing about the look on her face.