The certificate stored on the “clients” is the Public certificate from the FOG Server.
The only certificates to backup are in /opt/fog/snapins/ssl on the main FOG Server. As long as the public cert the clients receive match the originating server’s private certificate CA signature, all will be well.
So there’s nothing to do with the “FOG Client” install.
As of FOG 1.4.0-RC-3 the /opt/fog/ssl directory is backed up to other storage nodes as necessary too.