Has anyone out there retro fitted a hatch in the main cabin on a Super Seal?

On stromboli the cabin roof is moulded for the hatch, but one has never been fitted.

My question is when fitting the hatch would you have to make a filler to put between the outer fibreglass

and the inner roof lining and then clamp the hatch on either side? (I hope that makes sense 😀)

Cheers Brian