I was wondering about this, too.
Your script could copy default preset from the script folder to /data, then load it, on init(), I guess.
Alternatively, you can just put the preset in the same folder as the script (or /lib/etc.) and load it from there, I think.
They’re not saved automatically. You can set a metro to save them on a schedule though. I do that for state-recall with the script I’m working on now.