I've thought of this but it usually takes some time to overwrite a lot of data. I'm not savvy enough to know if there's a way to nuke the data that quickly, other than non-software methods.
A friend of mine used to keep a massive electromagnet in is PC tower, that would theoretically wipe the hard drives when switched on. We never tried it. (He wasn't dealing in CP, just pirating mass quantities of movies and music).
FDE best practices are to encrypt the entire drive with a random key, and encrypt that random key with a derived key (key-encrypting key, or KEK) based on password. You don't have to nuke the whole drive; just the sector with the KEK-encrypted drive key.
A friend of mine used to keep a massive electromagnet in is PC tower, that would theoretically wipe the hard drives when switched on. We never tried it. (He wasn't dealing in CP, just pirating mass quantities of movies and music).