CLEAR THRU WATERWAYS
The extra scuppers drain into the lazarette? They were probably drilled there by a DFO.
As I suggest in the post just previous to yours, it is no big deal to take the wedges out that are between the taffrail and the end of the toerail. IMCO they were put there to get the stern s,s half round trim piece to cover the seam. Probably the wedgies were added after the half round by the factory to make the boat presentable.
A couple of taps and the stuff popped right out of 338. Then the scuppers were carved down to deck level. That turns out to be lower than the deck/hull seam. Then you just fill whatever hole you might uncover and touch up with deck paint. The seam is covered inside with mat. You may go thru it a little, but just fill it with a ready made epoxy, it is not a strengh issue.
The s.s half round can be easily shortened a bit and put right back. It'll look like factory, and is probably the way they should have done it in the first place. The remaining exposed seam at the end of the toerail can be cleaned out of any filler and filled as well. Smoothed. sanded and painted it'll look great.