I have stayed between Yellowstone and Grand Teton over 20 times and never even knew they had a 6 person limit! Guess I should have read that material they handed out. Just go and enjoy yourself and don't worry about it. Nobody will even notice..
I would not be paying any extra for the extra person. Believe me the National Park entrance fee and camping fee for six will be more than enough...
You sound like a guy that likes to do the right thing.. Just don't look so guilty when you are checking in! LOL!
