It is unlikely that we would be any more familiar with law specific to OK than you are, though I can hope someone here is. I would ask your assisted living facility the answer to this, your hospice personnel. They are the ones who will be in the know on this subject.
That would be a question to ask the Hospice Nurse. She should be familiar with the State law. Its considered a restraint in my state of NJ and I know in DE. My Mom had a small bar to pull her up and the AL she was living in would not allow it.