I believe you will have to contact the program where you have been accepted to ask if they will allow you to defer. It will probably be on a case by case basis.
I believe USC is very theory based. I heard through the grapevine (so accept that this is merely a rumor) that they were dinged for this recently and are gearing up to be more hands-on. If anyone has anymore information on this, please feel free to correct me.
I feel like CSUDH is more hands on, but we do still have some research classes and the necessary theory classes. I believe Loma Linda (or was it Dominican U?) is very research based.
Once again, best way to find the answer would be to contact the OT department at the school you are curious about. I'm sure most won't mind talking about their programs to a potential applicant.