Linux Client -backup linux server /boot and efi partitions without snapshoting

I have a linux client with several devices and partitions. All bar swap, boot and efi are incorporated into various LVM volume groups as PV’s.
Thus; the urb client choices for snapshots for these (non-lvm) devices doesn’t quite suit my desire to keep these 3 as simple partitions.
HOWEVER, I like the idea of LVM snapshots or dattobd (device mapper) for all my logical volumes.
SO… I have used the “etc/urbackup/prefilebackup” script option to create a tar compressed (tgz) file in /tmp of “/boot” and therefore it’s sub-directories.
I have specified a virtual sub client for this task - as it is unlikely I will do much modifying of these filesystems and I want back them up infrequently.
IN order to ONLY create the tar file WHEN my particular virtual sub client runs - I have used a (documented by uroni) feature of checking argument three ($3) passed in to the script. This value is a unique number related to the position of the virtual sub client name in the web client configuration. Basically - 0=no sub client, 1=1st sub client, 2=2nd, etc.
The argument was multiplied by 100 for reasons I won’t go into (Uroni’s detailed explanation if far more informative).
All I did was execute my script via requesting a full file backup for my virtual sub client and echo what $3 was - once. Then I changed my script to test for that value (it could have been anything - it didn’t matter - all that I care is that it is unique to my sub client)…if it was - then do my tar czPf /tmp/Boot.Efi.tgz and exit (in any case) with a return code of zero so that the urbackup server would continue.
In the file backup web page - I choose / as the directory to backup BUT WITH the included files field set to /tmp/Boot.Efi.tgz.
So dattobd or LVM or whatever will setup their snapshot mechanism of / quite happily and then ONLY my /tmp/Boot.Efi.tgz gets backed up.

I did investigate imaging but, have read that Uroni and others don’t really recommend it for linux boot/root. Also, While I am happy with the reliability of LVM (and BTrfS for that matter) - I like my boot and efi (if present) to be plain, simple devices.
Hopefully this is helpful to someone.