Thank your suggestion. I will store a portion of the unencrypted wallet data on USB drives, but the remaining handwritten portion is not stored at my home.
I would recommend encrypting "seed phrase" into two complementary encryption keys using standard XOR operation. You would preserve the security strentgh and be able to recover without remembering unique, non-standard scheme. BIP39-XOR, SeedXOR, SeedTool tools (available in GitHub) demonstrate the concept.