pfSense to route between multiple subnets on same LAN

Solution 1:

As mentioned above, it is no longer an issue for me, but I have come across a potential solution:

As of version 2.1.5 (not sure about earlier ones), there is an option in System: Advanced: Firewall and NAT, called Static route filtering – Bypass firewall rules for traffic on the same interface. Checking this option will disable any filtering for traffic that enters and leaves on the same interface, aimed specifically at a scenario with multiple subets on the same interface.

I haven't tested it out (as the lab environment in which I needed this has by now been dismantled), but maybe it helps someone else...