Well, the InvizBox 2 with this feature has been tested by various tech sites and they are giving this little router a great review (just look here, there are also some print screens from the GUI: InvizBox 2 redefines what “privacy” routers can do | Ars Technica), so I think this setup would be less complex than configuring 4 routers to do something that could be done by just one. 
I think you should reconsider implementing something like that in your firmware, it would be very useful (I already provided the source code, so you could check how they have done it
)…