I have not created an "opening", but several decades ago I did remove both of the teak (veneer) backs. I removed the factory plugs and then the screws. At the time I was bleaching and varnishing the teak.
I recall the thought process that since those panels are normally covered (94%) by the cushion backs, there was never a reason to put plugs over those ss screws in the first place.
Lucky me, no prior deck seeps or leaks had ever caused a corrosion problem where the big ol' Navtec rods were threaded into pieces of aluminum round bar. It was a relief to confirm the present condition and to admire the strong FRP engineering that anchored the high shroud loads. It further confirmed our decision to buy an EY-constructed boat.
Further, you might find that creating a third opening, similar to the sizing of the present two, will satisfy you need for inspection and no door/cover will be needed.