Sharing AP - Guest and Internal

Hi

We are deploying wi-fi network. It will be used by internal users to
connect to the wired network and also by guests to browse the
Internet.

The solution recommended - On all AP, have two SSIDs, one for Internal
users and other for Guest users . Configure AD login via MS IAS  for
Internal SSID and simple shared key for Guest SSID.

For the Guest SSID configure IP filter an configure IP Redirect to
send all traffic on Port 80/443 to corporate Proxy server. No IP
filters for the Internal SSID.

First , is this technically feasible. Second is this secure. Third,
without additional software/hardware investment is there a way to
improve security ?