Mike
If its any use I have 4 reports on German sites on my website if its anyuse to you http://www.davidklyne.plus.com/european_campsite_index.htm
May I also suggest you try and get hold of the Camping Cheque site booklet as that deals with lots of sites in Germany. Although Germany has some very good campsites they don't seem to be as well organised as the French. There is, I think, a group called Azur, take a look at this link http://www.azur-camping.de/
David