You can the OpenSSH CA and put on the needed places.
For an usual OpenSSH client, put the following line into $HOME/.ssh/known_hosts (Linux, Mac) or "%USERPROFILE%\.ssh\known_hosts" (Windows) 
@cert-authority * ssh-rsa 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 openpgp:0xDA284583
There is also a shell script, which helps you to configure a server and sent a certificate signing request of the public key of the server to the OpenSSH CA.
You can your SSH public key (as .pub file)