5 pt harness and H strap

[Gent Matthew-EMG030 <Matthew_Gent-EMG030@email.mot.com>]

I've got a 5 pt harness (H style) that I swap between a few cars.

What do I do to the H strap to keep it from sliding all the way down?  If I
put it in front of the headrest it binds against my neck and shoulders, and
if I put it behind the headrest  it slides down the straps until it is
useless.

Is there some kind of clip that would keep it in place?  Duct tape would
work but I'd rather not get sticky stuff all over my new belts.

It shouldn't take much force to keep it up where it belongs, about a foot
behind my shoulders.

Matt