My work about unatended Raspberrypi SQM unatended station is based in two principles:
Mount a remote network based filesystem for store SQM data.
Ascript periodically executed by cron service that ensures that the PySQM is running and the remote filesystem is mounted.
The implementation of these two points was done a long time ago using the Raspbian version of that time.
Now that version is obsolete and the current one (stretch) uses a new administration tool called “systemd”. With this tool, it is possible implement both points 1 and 2 in a very easy, reliable and secure way… May be a day I will find time to do it…
But any way, my old solution is now obsolete and I do not recommend its use.
If, for study purposes you want to consult the old and now obsolete documentation, you can find it here.