Since all downloadable Whonix images are alike, the problem here is, how to detect in code which is the master Whonix-Workstation running the DHCP server?
Maybe the first Whonix-Workstation that starts and doesn’t find an already running DHCP server would start a DHCP server? Some room for race conditions. But ignoring race conditions for simplicity, that is easier said than implemented.
So it would still be a manual edit some config file process of setting up a multi workstation setup? Otherwise - since all downloadable Whonix images are alike - how would there be any other IP than 10.152.152.11 after first boot without manual change by user?
A wholly different solution I had in mind would be Any-Workstation-VM → DHCP-Server-VM → Whonix-Gateway-VM. But developing that is also a lot work.
Also, always good to ask: Why are we inventing something here? Why is this Whonix specific?
This is actually a missing (or existing in KVM?) virtualizer feature. Qubes instructions for multi ws are a lot simpler since Qubes automatically puts each ws into its own separate network and dynamically spins up a vif+ interface on Whonix-Gateway for each ws. Virtualizer feature request?