"file vault" is probably not a good way to describe it. File Vault is using an encrypted disk image for your home folder. What's needed here is merely an encrypted disk image.
I use a hybrid system here. I have a 10mb encrypted disk image that has my password list, software license codes, ssh keys, and some other things on it. It's "primary" location is on a usb flash drive I carry with me at all times. (64gb, bootable) When I make changes to it, the (locked) copy on my computer's hard drive gets updated. It's locked so I'm not tempted to make changes there instead of on the flash drive, which may later get overwritten.
I have a cron job that makes sure the dmg stays mounted. It can script the remounting without providing the password because the password is in my keychain. In this way I am able to keep my ssh keys there also, and automated jobs like rsync network backup via ssh key can run automatically. But if my computer is ever stolen, they won't have access to places I have shell access to by ssh public key because they cannot mount the disk image without my keychain being unlocked, which won't happen if they reset my login password. Same goes for my usb flash drive, there's no risks if it's lost.
