Curious, why do you want to avoid SNI?
SNI transmits the host unencrypted, that is a real security issue.
Systems that hostname their customers (mycompany.example.com) should use wildcards for that scenario instead of SNI, among other reasons. That’s the only possible concern I can imagine.
Multi domain certs help but then you need to encode all the names ahead of time and if you miss a name you need to reissue and reapply the cert.
Otherwise an adversary could simply see what IPs you connect to and reverse DNS them.