Archduke, the Haans device connects to the back of your helmet and the seat, so your head doesn't snap forward, hence not being able to wear one without a helmet.
And Vetteboy, I'm not worried about wheeling injuries, I know my neck won't be snapping forward if I was to hit something, I'm worried about getting into a accident on the street, because this is going to be my Daily driver too.
I did just realize, can I mount the 5th strap to the seat? I think I might weld a bar in between the brackets and attach it to that. Is that ok?