Data-only backup with 3.6.2

[mschmitt]

I've just upgraded my main Mac to Catalina (was stuck on Mojave due to 32-bit apps). I do have full clones, one on a SSD drive.

But I have two other 1.5 TB HDD drives, which I rotate offsite.

For these drives, making a bootable backup doesn't seem to be a good idea; for one thing it would be problematic to boot from them to enable encryption. Another is that they're tight on space if I try for a bootable backup.

Ideally I'd just backup the Data volume. I see in the blog mention of a data-only backup in 3.5 and later. And it says that a data-only backup to a pre-encrypted volume is supported. But how?

As an experiment, I selected the standard "Backup - user files" script, but it still gives the warning that "Encrypted volume is incompatible", suggesting that I erase and copy.

So I'm not sure what my options are.

I saw mention in another post that you may be able to use 3.2.5, but then how would you have two versions of SuperDuper installed at the same time? They'd compete for settings.

Is there a way to use 3.6.2 to backup the Data volume to an encrypted drive? If not, what is the procedure for backing up the Users folder (plus maybe a few other non-system folders) to a pre-encrypted drive? If not, will Catalina let me encrypt a non-bootable drive?