Multiplexing on 443 - obfs4, tls, openvpn
When packets arrive on a gateway on 1 port, it could be possible to multiplex with a regex, like sslh does. By forwarding the expected openvpn traffic to openvpn, same for web traffic to webserver, you could presume that the rest is probably obfs4 traffic. TLS and obfs4 both expect that the client talks first. Another - but slower - approach could be to pass all incoming traffic to obfs4, if there's no answer after X time, pass it to the revers https proxy.
For more background we could read about 'decoy routing, aka refraction networking where they embed a stego tag in the random bytes of the tls handshake to say whether it's normal tls or it should be treated specially.
Thanks to arma for explaining this setup, however I'm going to close this feature request for now, because I think we don't have the time to do this in the short-mid term.