It seems that one can setup an "automount" that will make systemd automatically mount when a mount is accessed . It's unclear if this also applies to mount failures or just "not ever mounted". If someone wants to try, I think we need something like this:
The systemd unit file must be named systemd-escape -p --suffix=automount <HOSTPATH>
Then, create a file /etc/systemd/system/<unit_filename_from_above_command>:
[Unit]
Description=Automount of hostpath
[Automount]
Where=HOST_PATH_HERE
[Install]
WantedBy=multi-user.target
systemctl enable <unit_filename>
If that works, I can put this in our code (for volumes and backups).