Cisco :: 5508 / 4402 - Office Extend Suggestion

I have attached a diagram of the current topology. At present, we have two 5508 connected to our core. We also have a 4402 behind the firewall (DMZ) just purely for guest access. So the staff users connect to the access point which in turns connects to the Staff WLC 1 (if this fails then to Staff WLC2). any guest user connect to the access point which in turn connects to Staff WLC which anchors to Guest WLC which then provides access. Since the guest is behind the DMZ they can only access the internet and not out internal network.
 
Now we want to office extend our network - we want our users to use 1132 AP at home to access the Infrastructure. is there a way we can do this without disturbing the existing infrastructure. On reading Cisco website, i know the best practice is to use 2 5508 (one behind the firewall and the other anchored to this access the internet network ) i thought since we have a Cisco (dmz) switch (48 port) and only the 4402  (Guest WLC) is connected to it, maybe purchase another 5508 WLC and connect to the 48 port Cisco (dmz) switch. will this work?