When you create the guest user you will want to make sure the account is valid for 24 hours but only active for one. Clearpass has a black list that it keeps of expired accounts where if the user tries to connect it will deny access to that account.
Its been quite awhile since I have built one.
You will want to use one the following settings that best fits your needs
I believe you will need to use
expiration_time (account lifetime)
expire_postlogin (account active time)
Ill ping one of the devolopers and see if they can chime in. :)