Many of these are secure schools (I think thats the correct terminology) and they are certainly not prisons. But in terms of the secure nature, the need to prevent absconding, the risks that may arise if the supervision is not maintained makes the prisons guidance about the only appropriate, available national benchmark guidance from which to start.
Of course when dealing with the client you will not refer to the prisons guidance directly in these cases other than in the small print of the bibliography at the back of the report. Or perhaps we are overlooking something more relevant?
We had a similar problem in the early 1980s - do you remember when when Norman Tebbit devised his "Short Sharp Shock" boot camp strategy for young offenders and "Childrens centres" were set up all over the place with no expense spared.