If you don't add a hatch up forward you might need more hardware for the rail hardware... well nuts.
Could you, please, provide more detail of recommended 'nuts'?
"Well Nuts" are an inverted rubber "top hat" with the nut sealed in the bottom.
They insert through a hole from the outside.
Tightening the bolt squeezes the nut and rubber up against the backside of the surface.
This keeps the nut from pulling through and seals the hole, at least in theory.
https://us-browse.startpage.com/av/anon-image?piurl=http%3A%2F%2Fwww.calsci.com%2Fmotorcycleinfo%2FImages%2FWellNuts.png&sp=1595908054T1c0d8849413e8516d4d8792446611eb509ab16732d66aa3cfc21ffd16b733375