Much thanks Warhead. It does look great with the rock raider helmet - sadly those aren't really an option since they appear to be pretty rare. There's only 2 black ones on the entirety of Bricklink
Since my shock troops wear space armour it might still work with the aviators though trying trans-red visors to fit with the colour scheme is tempting too. I'll see what I'll make of it, after all, it's not something that's too pressing.