Re. The night sitter. Is there any reason why you (using your dads money) can't employ one privately? You don't need approval from SS to do that.
However surely a night sitter isn't going to be able to stop your dad leaving the house either? They can't physically restrain him and won't he get just as agitated being 'kept a prisoner' in his own house as he was in the CH? I wouldn't want to be the carer in a 1:1 stand-off situation in the middle of the night. At least in the CH, there is backup staff if your dad gets aggressive.
As I've said before, my mum was a daytime wanderer, but that was no less difficult to deal with. There was no way I could prevent her from walking the streets, cold, bedraggled and tired and being rescued by strangers after occasional tumbles. That last Christmas where I described driving around the countryside with her on Christmas Day was the final straw for me.
I'd gone down on Christmas Eve and of course she was out, goodness knows where. When she eventually arrived back home, she was really distressed. Confused, cold, hungry and probably soiled as well. And that was it for me. She wasn't coping at home and I made the call to the CH of my choice the day after Boxing Day.
Perhaps paying for a private carer to take your dad out during the day from the CH would be one possible solution in the longer term? I wish I'd thought of that with Mum in the early days as a 'friend' was what she needed more than anything, before she finally settled in.
She was also better than the 'poor old souls' when she first went in (as are most newbies) but eight years on, she was one of them herself, slumped (due to the Alzheimers, not as is often presumed, boredom) in a chair, dozing for most of the day. I loved it when new residents came in who were able to communicate with the staff, because it provided the 'poor old souls' with people to watch and listen to, even if they couldn't join in.