Hi John, Deploying via vSphere client (launched from vCenter) is not optional I'm afraid. Hidden somewhere in the troubleshooting guide is a sentence stating that deployment of SCG using ESXi is not supported. Had that same sentence been included in the pre-reqs section of the user guide it would have saved me a lot of time! You can get a 60-day free trial of vCenter (VCSA).  Hope this helps.
I deployed the secure connect gateway via the ovf package for vmware using version 5.1400.10. Appliance deployed but hostname and IP info entered from ovf template are not present. Can't login via console and webui is not working. Have tried this on several different IPs and subnets. Also tried the 5.1200 version as well and got the same result. When appliance is starting up, I get this error:"Waiting for SAE to start...Secure connect gateway could not determine the IP address to connect to with the WebUI."  
secure connect gateway 5.1400.10, no config from ovf or webui working.