Nothing says you cannot trivially encode the paper password. Those in the know understand that you need to append “BoomShakalaka”, replace “A” with “Q”, or some other super simple modification to what is recorded.
Maybe the NSA would be willing to brute force the infinite variations from that starting seed, but it is still effectively locked for mortals.
I've thought about making a "word search" and embedding the passphrase in it using a pattern (e.g., a subset of a Knight's tour, a space-filling curve overlay, or some other sampling algorithm).
If you add an explicit reminder to check the email where you explained the modification, then the idea seems solid. Tough at that point put half the password on paper and send the other half to a whole bunch of trusted people.
Maybe the NSA would be willing to brute force the infinite variations from that starting seed, but it is still effectively locked for mortals.