@hatshepsut93:

Your method does seem viable. So long as your key is kept secret from the bad guys seed B will reveal no information about seed A. It reminds me of the "optional passphrase" feature of the BIP-0039 standard as described here: https://github.com/bitcoinbook/bitcoinbook/blob/second_edition/ch05.asciidoc#optional-passphrase-in-bip-39 and here: https://blog.trezor.io/hide-your-trezor-wallets-with-multiple-passphrases-f2e0834026eb

OPs method and yours could be combined such that:

(A + B) % 2048 = S; decoy seed with small amount

and

S + "secret key passphrase"; as per BIP-0039 leads to the main wallet