We run Pylon Anywhere with the Systems Management add-on. This allows us to blow away (hard reset) the unit and wipe SD cards remotely. All the user has to do is call me and I can intiate a synch to have it destroyed. We also have forced power login, three times wrong and it hard resets. We also have enabled 30 day required sync, if it doesn't sync in 30 days, hard reset.
All traffic to Pylon Anywhere server is encrypted too.
Not much more I can do.