Public Camping

Contrary to what people have told you, wild camping is illegal in most European countries. It's supposedly legal in Norway and other parts of Scandinavia .

Legal undercertain restrictions (out in the nature in Scandinavia+other Nordic countris minus Denmark).
Then there are the public owned extremly cheap camping areas with (some facilities) in some countries like France - look for the name Camping Municipale

My friend had his truck with cab-over shipped to Europe where he spent over a year traveling around, and sleeping inside. I don't think he ever actually spent a night at a campground. He says that public parking on the streets is abundant, and he had a small propane stove inside too. There is a camping organization where you could become a member, and get discounts at the campgrounds.

Well, wild camping is illegal in most European countries - BUT it's done anyway. Some countries are more relaxed about it than others. Summertime is always the harshest, and the police will not tolerate camping anywhere, but if you just stay one night at a place (there's a difference between camping and "overnighting") and leave without leaving a mess behind, it's actually NO PROBLEM. Some areas are very dry in the summer and open fires are not allowed for obvious reasons. Be sensful with your cigarettes, too...Those fires that did not be lightened on purpose are often caused by cigarette buds. Also, bring a little showel or so to dig up a hole for your dumpings. You certainly need to carry some sort of identification on you (which you have anyway), so officials can see you are a tourist and not an illegal immigrant ;-)
Generally, show respect for the environment you are camping in, and you won't have troubles. Many farmers will let you stay in they hay barn as well, especially in cold and wet weather. All you need to do is ask.

While the fall is a great time of year to travel for many reasons (fewer tourists, lower fares, great weather), camping is not one of them. In France particularly, when October rolls around, many campgrounds close up shop, certainly by October 15. Last fall when we cycled France for a month, we lived rough half the time out of necessity. And while living wild may be illegal, using a bit of discretion makes it rather easy. You know, wait until the edge of evening to set up your tent and pack it up at an early hour. Bon chance!