Finally I use Folder Sync to keep all of the userdata files on my phone backed up to a folder on my server via SSH. Images are synced immediately on creation, and everything else is backed up on a schedule.
On a similar tangent, I use Syncthing-Fork on my phone to sync my userdata between my phone, desktop, laptop and VPS.
I use the untrusted device feature to encrypt my data with an additional password, which I entered on my phone, desktop, and laptop, but not on the VPS. That way I have an encrypted copy of my userdata that I securely store on my VPS for an extra layer of protection in case of a security breach.