My PX-10 came with a Cyclone GT attached to it. Instead of threading the dropout, they filed down most of the threads of the hanger bolt and attached a nut on the backside. Pretty weird solution - I'm just glad they left the dropout intact.
I have several different sized Suntour hanger bolts. I have seen some that slide all the way through the simplex drop, and are then nutted from the other side. I am not sure that I can put my hands on an example right away, but I will look about. I am not sure what was done about the stops.