Doesn't cover the scenario I outlined.
Step 1 then becomes "buy airline ticket to get home so I can get at the safe".
Sure, of course doable, but a million times more cumbersome.
What if passport was also stolen? Maybe in such a time it would be convenient to be able to contact anyone? Even if not to solve the situation but more of a heads-up.
2. Add both for each site you use it for
3. If using gpg keys you masterkey lives on a USB key, use subkeys which get transferred onto both yubikeys
4. Lock one the USB key and 2nd yubikey in a safe* with the password you never use
5. If you lose your day to day keys, unlock safe
*safe can be an actual safe, a "secure enough" place in your house, a bank safety deposit box, etc... You can also have multiple safes, one on site, one offsite.