As, I think most of the information shared is accurate, you may need additional strategies. In my experience, 1. If a campsite is full, ask a camper if you can put a tent up on their site. 2. Never ask local police but do discuss your issue with the fire department, if there is one. They are often helpful. 3. Approach a local Church. They may open a piece of their lawn. 4. Depending on how rural, a business that has some land, like a convenient store, might be obliging.

Having said all this, I would recommend you plan your stays and make the appropriate reservations as to not be a burden on others except if a problem happens causing your timing to change.