I did this for backups, you can try if it works for your DB too, just do some tests because is a workaround, not an official way (but i found this solution with Adam).
I created a new server for that role, without the public IP (with only a private one like 192.168.168.168). The panel, in the same network, had a public IP and private IP (example 192.168.168.167).
Before install enhance, i edited file hosts in the new server, writing like:
192.168.168.167 panel.domain.com
Then, installed enhance to link with panel.domain.com. The traffic passed from the private network, and I correctly see the server with the private IP in the dashboard. The traffic for that server should pass via private network. For me everything works.
But again, can't confirm for you, just share my similar case and do some tests about DB too 🙂
EDIT: However, keep in mind all the pros and cons of having a "closed" server in a private network, without the possibility of communicating with other servers in other providers or datacenters!
