So you have 1x 7220 as MASTER in DC1 and 1x 7220 as LOCAL in DC2?
OR do you have 2x 7220 as MASTER/LOCAL in DC1 and DC2 (SUM: 4x7220)?
Normally you won't terminate a RAP on a MASTER, but you can do that if you want.
I would recommend the loadbalancing on this way:
Reserve two public IPs for the Controllers.
Create two AP-Groups.
AP-Group-1, LMS-IP: DC1, Backup-LMS-IP: DC2
AP-Group-2. LMS-IP: DC2, Backup-LMS-IP: DC1
Now you have to provision the RAPs in the different groups and you load balance them "manual".
But you can do that with the F5, too.
Regards,
Thomas