Hi,
I'm looking at
http://www.camping-laacher-see.com/de/Start.html which is my first stop north-west of Koblenz and
http://www.campingstubai.at/ for my second stop which is south-west of Innsbruck. Both look stunning and more than adequate to pitch the small tent up for something to eat, freshen up and a kip. The Austrian one especially looks gorgeous.
Google maps is great for searching for things around your route. I found both of these simply by zooming into roughly the time intervals that I wanted to stop at and searching for campsites nearby.
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