Overboard drains

So this past weekend I had to dislocate almost every joint in my arm to replace the overboards for the fish boxes and live Wells. For anyone out there that has a late 80's sailfish, how do you replace the drain in the bottom of the stbd fish box behind the captains seat? I cannot fathom how you are supposed to reach the nut let alone get a hose and clamp in place.
Also something that has come to mind while stuck in that small space is why Grady decided to carpet the area under the helm where the trim tab pump and shower sump live.

The only idea I can come up with is to actually cut out the drain area in a larger diameter and make a flange that can be screwed and glued back down with the drain in it. Not sure how well this will work, but I figure it's worth a shot.
It's either that or I will have to pay a shop to do it, which I would prefer to avoid. What did you do with the carpet under the helm station in that cubby? Did you leave it or remove it. I'm strongly considering removing the carpet and leaving it bare fiberglass.