Since I moved to Europe and started reading this forum, I've noticed that it doesn't get much traffic.
I don't have much experience with cycling in Germany, but I am posting to suggest that you check out the travel diaries at the
Crazy Guy on a Bike website, and look specifically for some of the
270 journals about touring in Germany (in whole or in part) that users have posted. In my experience, most of us Crazy Guy users are happy to respond to questions about the places we've toured if our journals don't specifically address what you want to know.