I think more useful would be to be able to boot into another data partition with a different password, which, in turn, would hide the other "daily" partition. I believe LUKS is capable of that. The storage dump looks like a random set of data and only a valid password can find and decrypt a matching hidden partition.

Ideally this should also work on lock screen, e.g. if you type in a non-standard PIN, it would boot from the "dummy" partition in the background, with a slight delay perhaps.

This way you don't have backup anything (I mean you should, but for normal purposes) and have a plausible deniability whenever you get randomly inspected, not just at border crossings that you anticipate.