I also did a little adventure into local-anon-messaging, but my solution was to use wireless access points and udp for text, relying on a server only for image share. In retrospect it is primitive and ugly as sin, but I was excited about it so I put it on the app store:
https://play.google.com/store/apps/details?id=com.constantiz...
The only problem? wireless routers that block udp ;)