If you use a different port, e.g. 443, with the help of dpi, the ISP still sees your openvpn traffic. A good solution would be to wrap the traffic in stunnel. Therefore, it will be indistinguishable from obychnogo https traffic.
But to use the ssh tunnel is much easier and less work with the setup.
Is there a good guide on the hack as well as install the openvpn in stunnel. On github there are also pre-made scripts.