Yeah if you're looking for long term it needs to be archival media. Many people think the flash drive will hold it forever but they are potentially the most fickle.
I forgot you could use SSH port redirection. By having them connect to your ssh server. Just understand that you need to configure it in a safe way to avoid someone using the credentials incorrectly.
See the section called "Exposing service running in localhost of a server behind NAT to the internet"