I wish I hadn’t been so stubborn about sticking close to plugins in the FreeNAS GUI. This script addresses all the issues you’ve identified with the Plex plugin. Love it!
Just one observation. This is an extract from the installation notes…
$PLEX_CONFIG_PATH need not exist before running this script; if it doesn’t, the script will create it. The script will also set ownership of that directory to the user/group IDs for Plex Media Server. If this directory already exists, it must not be using Windows permissions.
When I first ran the script, I went looking for the directory in the FreeNAS GUI. It wasn’t visible. I found it through the Shell instead. I decided to destroy the created jail and remove the directory. I then created $PLEX_CONF_PATH beforehand as a dataset rather than as a directory. The advantage for me is that I can easily see the size of Plex configuration data from the GUI under Storage > Pools. I found this step useful.
EDIT: I just spotted some discussion about this further up in the thread. While I understand your concern about not creating the dataset within the script, I wonder whether the installation notes could be revised to make this point more visible?