Nutplates to wingtips for Strobes

I have drilled and cut out space for my Whelen strobes. What's is the best method to attach the strobes; screws with nuts behind the fiberglass or nutplates. If I install nutplates can I buck the rivets?

Thanks.

I used nut plates on mine. You are likely asking due to the tight space and cannot get a squeezer yolk in there. You can use pop rivets.