I've created a new CSimNetBoard class which can now run both Daytona 2 and Le Mans 24 in linked mode. Also, I've made it so that Daytona 2 now supports more than two machines; I've tested six linked machines and they work, though my PC wasn't powerful enough to run them all at full speed (I have a Ryzen 5 1600). Le Mans 24 might work with more than two, but I'm not sure just yet.
I've uploaded a new build here. Also I've attached the new SimNetBoard.cpp file if anyone wants to take a look at it.
My next step will probably be to add more games; I'll probably start with Scud Race as hopefully it will be somewhat similar to Daytona 2.