(a) Since you should be storing your private key on a Yubikey/Nitrokey type device, take it with you wherever you go. To be clear, I'm not advocating doing remote admin tasks from an untrusted computer, but in a desperate situation you could do it from a semi-trusted device with a Yubikey/Nitrokey since it won't be possible to extract the private key (and you can set mandatory Touch + PIN policy on the key to prevent malicious software using the hardware token in the background without your explicit consent).  and/or 
     (b) Implement an SSH CA and use that to generate short-lived emergency keys (e.g. https://smallstep.com/blog/ssh-emergency-access/), someone "back home" could send you a short-lived key in a secure manner.