I have edited my post 16 above to add a very important word that I left out.
That said, when I opt out of the BSX or the non-ATR MMW, I do not just say "I opt out." I say, "I opt out and I need to be able to see my belongings. I will move to a place where I can and if that is a problem get your supervisor and an LEO as your SOP requires that I keep visual contact with my belongings." And then I do.
Do they get huffy? Usually. Do I care? No.