Moving the DHCP scope for your AP's would probably be most elegant. Where is the gateway for your AP subnet?
Assuming that the gateway is on your core (not the Aruba controller), simply recreate your AP scope on your server, then add an IP helper to the config for your AP subnet, just like you do for your user VLAN's.
To make the transition more graceful, create the scope, but keep it disabled. During your maintenance window, add the IP helper and activate the new DHCP scope.
Hope this helps!
Jay