But memorizing your seeds is really not that bad. You just need to work on memorizing it until you can confidently say you remember. Don't you memorize your passwords, also? So seeds should not be any different.
But to be honest you are being very paranoid. I doubt anyone will try to search your phone/laptop/whatever just to find your Bitcoin. And even if they do, unless you give them access to the wallet, they are not getting in.
I have come to the conclusion that customs will not search your personal belongings, such as your cell phone, unless you give them sufficient reasons to draw their attention to Bitcoin. A wallet installed on your cell phone is undetectable and without much effort you can find apps that hide certain apps of your choice.
And if you prefer, you can delete the wallet app and memorize the seed (with or without a passphrase). You can keep a copy in your home country so that you do not rely exclusively on your memory.
Memorizing a 12-word mnemonic is not that difficult. Remember that if you encrypt your wallet, shouldn't you remember your encryption password to access the wallet? In this case, it's better to memorize the mnemonic directly, and anyone can do it. I myself have memorized one of 24 that I no longer use, and I have more than 1 memorized.