The seed is just a few words. Who says it has to be written down on something anyone can physically find? You can store the seed as a txt file in encrypted form anywhere in the world. Stick it on a few SD cards and tape them to a few different places.
Hardware wallets often also offer a 25th word to encrypt the seed. That's going to be rather easier to remember than the other 24.
Software wallets that use BIP39 also allow the use of additional word, which basically is a password, and in terms of security is equal to your advice of encrypting the seed - both ideas fully rely on the strength and secrecy of a password.
There are some more advanced schemes, like Shamir's Secret Sharing, which allow you to split a key into chunks, where each chunk is useless on its own and doesn't provide any information that would weaken the encryption (unlike with naive splitting of plaintext key).