I'll try this in a couple of days when I do my monthly offsite backup. Worked OK last month.
Just finished my montly backup with this, and it worked.
It is a little different than I remember from last time though. There is no checkbox for running the script in the background, I assume because it always runs in the background now. Also, when I push the Mount button, it does mount and run the script, but the Mount button just sits there "spinning" until the script completes. Not sure that is expected behavior or not, or whether I would even consider it a bug, but it might be a little disconcerting if you aren't aware of what's happening. Once the script completes, the button does show the drive is mounted. My script doesn't take any action on the unmount, so that happens quickly. Don't know if it would also "spin" if the script did anything or not.