Do not scramble the seed words. Do not write the words on random pages in a book, Do not change the order of the words. Do not omit one or more words. Do not encrypt the words in a MS-Word file or Veracrypt or anything. Do not write only the first four characters. Do not write the index numbers of the words
All those things corrupt the fundamental purpose of the BIP39 recovery design - recovery
The chances of losing your coins because your obfuscation method was too confusing (later, when you need to do a recovery) are about 1000 times higher than the chance of being questioned at an international border
Do not store the seed words in the cloud, or anywhere electronically. This has two risks. The cloud is not a reliable storage method. The cloud is accessible to the entire Internet
The BIP39 specification has a passphrase option
Write the seed words on paper. Carry the paper. Keep other copies in safe places
Make two wallets (or 2 accounts in a Trezor or other cold wallet). One account is the seed words and no passphrase, with a few thousand Satoshis. The other account is the same seed words and a strong pass phrase, for your Bitcoin
Make a 6-word diceware passphrase. Add one random alphabetical character. This is easy to remember, and 81-bits secure
https://theworld.com/~reinhold/diceware.htmlMemorize the passphrase
At the border: if you're questioned about your cold wallet (if you're carrying it), tell them what it is. If you're questioned about your seed phrase, tell them what it is. If they want to see the Bitcoin wallet, use the seed phrase to recover the no-passphrase wallet. Show them your few thousand Satoshis. That should be further than any border guard could possibly understand, today. In the future they may be better trained. Or you could be a special person (read about the constant border harassment of Glenn Greenwald and his partner for years after Greenwald reported on Snowden). If they ask whether there's a second account, you don't understand how that's possible. Your device has only one wallet