Yes, you can.
Create a share using a specified path (as opposed to the default path) pointed to /lv000x (the LV you wish to back up).
CONFIGURATION -> NAS Resources -> Create new share
Then simply back up this share. As long as the share is the only data folder on the LV, you've essentially backed up the entire LV.
Note: You'll need to create a new backup database or move it to a different LV.
