But you accept that with any channel that isn't angled and very deep. Some channels have small scuppers located in the aft channel that would help but I don't want to put holes or otherwise cause spots to get clogged.

Instead, this cockpit was designed to drain the widest part of the seat deck at the base of the coamings. There they put deck scuppers to lead spray that can fill the area outboard of the locker lids. They keep the seats drained on a heel I've found, leading water overboard. Quite a bit of water has to fill up before much of it reaches the locker lid drain channel(but then it will go in the bilge). I'm putting those two small scuppers in the same place on the new cockpit.

But it is rain that is our biggest problem when coastal cruising. Not often in our type of sailing that the cockpit gets too heavily doused by waves. But rain, we get lots(but we don't sail in it that often )