For example, I've got a wireguard setup that~ you connect to the public wireguard setup, then I have an internal nebula interface that is meshing all the internal systems together. Instead of wireguard masquerading and forwarding from the default eth0 device on the server, everything leaves via that virtual nebula interface I have setup talking about wildly different things though, but should still be achievable in that type of manner. I'd hit up a microtik forum though. Somebody there will probably know if its even possible with RouterOS