I have heard of this being successful, but not to a VCC server, only to a standard B&R server and with the correct ports open. As far as I know and can think theoretically about this, it does not seem possible through a VCC gateway. And to be honest, the system is not build for that
However, we are working on the next release, and we are gathering information (without promising anything) about scenario's such as yours. If you can, we would appreciate it if you can give us as much information as possible about your specific use-case(s). Are we talking about endpoints alone? Are you a VCC on your own premises or use a cloud provider? Are your clients mobile workers and so on...