It has been my experience in the past when dealing with the government or even businesses, that trying to make things right usually causes me (you, us, anyone) a lot of trouble or even more expense. One more thought and then I will tell you my suggestion; a Ranger or some official should have visited your site with instructions to leave, etc. / thankfully they did not lock you in!!! lol. Doing nothing will not remove the guilty feeling although I really do not think the people in charge of the campground cared what you did. Otherwise, they would have made contact with you. You can donate an amount of money you feel is correct for the services you received to any non profit organization; and sleep well!!!