Hello,
FYI:
The folks from Café Netzwerk (http://www.cafe-netzwerk.de) kindly offered that we can sleep at their venue, or use their kitchen for cooking, or deposit stuff there. Café Netzwerk is located about 10-15 minutes by foot from the main venue. The only drawback is that they don't have beds or showers, but as a fallback or geek sleeping location, it is ideal. 
Florian