Older thread... and not sure if this is useful to anyone, but these helmet bolts were recommended on the pathfinders forum. https://www.amazon.com/Fibre-Metal-Honeywell-FM4001-Quick-Lok-Adapter/dp/B002BUMS8Y/ref=psdc_7491811011_t1_B015MG1SMK
They are not black so you'd have to paint them, but they are concave if you prefer that look.