Tried rivets initially, but found that they caused a star effect on the glass - no problem for you with aluminium body.
Have you seen the bolts used with the button heads.
Assuming you are using an aluminium scoop etc. try using stainless button head bolts with the hex (Allen head)
You do say your want the rivets but thought the other may be an option with the larger scoop may be worth a comparison. After using them I think they look a little better than the rivets.
Cheers
Bernie