[chlorion]

You can just wipe the luks header as a nice middle ground.

Luks uses an anti-forensics algorithm that requires the entire volume key being available to unlock the disk at all (it combines the blocks of the key with some diffuse algorithm and xors stuff together to form the actual master key), so in theory you can just clear one sector of the volume key and the whole thing should be unrecoverable.

What I mean is that if even one block of the key is missing you can't guess the rest easily.