Thank you, I've been reading up on fileparse.
The input for "fileparse" has to be key=value so one would have to get a continuous update into the file.
As I'm receiving data off site this would be an issue - I can't expect - not consistently - a stream of updates.
Second, the data I'm receiving now comes as a CSV, so I would have to rewrite into individual events, or just tap into the "Device" table and send that.
Third, there does not seem to be any unit conversion, "wee_import" does support this.
So as I appreciate the feedback, and I really hope it will be useful for somebody else down the line, it does not quite suit my use case.
However, by experimenting I've found out that I don't really need weewx to be running.
"wee_import" will happily create the database - with input from weewx.conf and "wee_reports" will create the appropriate reports.
So to answer my own question.
- Install weewx
- Configure weewx.conf
- Disable weewx from starting (systemctl disable weewx ; systemctl stop weewx) ymmv
- Configure the "wee_import" input config file
- Run "wee_import" to import
- Run "wee_reports" to create the reports.
I wrapped the latter in a script which I can "sudo" from the remote source which ships the logs to my server.