When I plan a trip and make reservations ahead of time, I stick to the schedule. I make my schedule reasonable so I have never had any of those situations you mention come up and throw my plans off. I've only been camping for 12 years so there is still time. If such a situation was to occur, I would simply call the campground and tell them I am going to be a day late, I'm cancelling or whatever. But It's not rocket science. I don't get lost in outer space if I miss my scheduled time of arrival, my plans aren't made for 17 different campgrounds in 17 days. They are more likely 4 campgrounds in 17 days.