Hi jeronimo,
using a separate VR for management is a possible solution, but this still needs an additional logical interface on the VPN gateway. This might be a problem if you are buying a VPN service from a provider who accepts just an untagged transfer VLAN.
As Ronald writes in
https://community.extremenetworks.com/extreme/topics/recommendation-for-configuration-of-management-..., you can connect the management port to a front port and layer 2 switch from/to it, but I do not think that you can use that to route on a switch to its own management port, because the switch has just one MAC address.
The SecureStack EOS host VLAN should not be used at all if the switch is used as a layer 3 device.
The N-Series switches had two IP stacks, one for managing the switch, one for routing. The host VLAN, IP, and gateway were used by the switch IP stack, and a router interface in the same VLAN on the same switch could be used for routed access to the switch management IP. This changed in CoreFlow EOS version 7.
The two EOS switch product lines (Broadcom based and CoreFlow based) have quite different operating systems. [The line has been blurred by the 7100 series, which is Broadcom based but uses the same EOS as the S-Series.]
Br,
Erik