Howto integrate SSL Proxy Feature into ISPConfig 3?

[Master One]

I already posted about that matter in 2008 for ISPConfig 2 here.

Has that feature been incorporated in ISPConfig 3?

As I guess not, is the shown solution still valid for ISPConfig 3?

A SSL Proxy is must-have feature, because I want to pay only for one normal SSL certificate, and use that one on https://ssl.masterdomain.tld, so that all other hosted sites can be accessed by https://ssl.masterdomain.tld/hosteddomain.tld/, instead of having to pay for a wildcard cert or multiple individual certs.