permanently attached USB SSDs are supposed to be mounted

Just mount them somewhere under / device, so if a disk/mount fails the mounts depended on the path can´t also fail.

I keep my permanent mounts at /media/ and I have a udev rule, that all auto mounted media goes there, so /mnt stays empty. A funny case is that my projects BTRFS sub-volume also is mounted this way, although it is technically on the same device.