You'd maybe get more replies from the 'Abroad' section, but this website is very useful for finding overnight sites:
http://users.telenet.be/leo.huybrechts/camp1.htm
You just select your chosen country, and chosen route, and all the sites within 15km of that route will be listed, in a north/south direction. Sites open all year will be highlighted in red and brief details given so that you can look them up on the internet. Just a suggestion, though, check that they are open before turning up - some continental sites have a habit of altering their opening dates to suit themselves, sometimes!
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