Options for Running SSH on Windows 10 With .pem File on USB Drive

I use SSH on Windows 10 to manage my server. At the moment I’m using the Windows supplied OpenSSH and a .pem file located on my hard drive that I’ve changed the permissions on so OpenSSH will allow it to be used.

I want to move all my files to an encrypted USB drive. However I cannot change the permissions on the .pem file when it is on a USB drive, so OpenSSH won’t work with it.

Does anyone know of another option for running SSH on Windows 10 that will allow me to get around this issue?

Thanks!
Antony.