While doing the dry fitting of the companionway hood and slide tops, I noticed that the width of the bevel on the top of the slide trim piece was very slightly narrower than that on the hood.
I must have used a slightly different bevel measurement on one of them.
No matter. I slimmed down the bevel on the hood trim with a block plane, and until it matched the slide. As here.
It's very awkward doing this because the piece cannot be held in the vice, but with patience it is possible.