Multisig's vulnerability has been a concern of mine too. But so is a single seed. It's so easy to have your seed compromised or stolen.
So if you're going to use a single seed configuration I think it's essential that you also create a high entropy bip39 passphrase\password too. For cold storage.
Then back it up, and store it separately from your seed phrase.
Of course if you lose your bip39 passphrase\password you lose access to your funds for EVER!..๐ฉ
Keepass can be a very powerful tool to create, store and access your passphrase\password with.
But keepass takes some study to use well. Maybe I can do an instructional video.
And don't forget about Super Shamir. You can combine it with bip39 for seed security and backup..๐งก๐