I played around a little on my 12S, also wanting rubber pegs for the passenger. If you put Knight Design (1.5") or Goldwing (1") lowered pegs back there, they will not fold up since they do not have a detent like OEM. You may also need to source new springs if you want then to remain down.
I would think that Norge passenger pegs would swap right in but would not be any lower. They should fold up like the current 12S ones.
I ended up with brand new Goldwing pegs (eBay, $35 from a trike conversion) that were perfect. Wider, longer, lower, rubber-topped. If you've got a pillion often, I'd consider those for passenger pegs also.