Take a look at the
ADAC camping web site. (
German auto club, like the British AA) They have an online camping guide for
Germany and Europe that shows many campgrounds.
It is in German, but quite easy to navigate around the maps with just a little bit of German. From the main page, click on "Zum Camping-Caravaning Führer" which is pretty much in the middle of the window. In the new window that opens, click on "Ziel" (goal or area you are interested in). Type in "Bodensee" into the text box, and click on "Finden". You can then decide whether you want to further narrow down your search by country (A=Austria, CH=Switzerland, D=Germany) or even town, or else just click on the first link given for a map of all 28 campgrounds around Bodensee that they have in their database. Clicking on any of the triangular campground indicators on the map will give the address, contact info and further details.
Cheers!