Well I can understand how you are having leakage at the companionway.
I finally changed the hatch boards I had to 1/2" Lexan, 3 pc. ship-lath. I love the change but I made that change to allow light into the cabin as part of my never ending battle against the dark and evil forces of mildew.
Here's what I can find of that modification. I originally made copper to line between the molding where it is laminate and later made it of st.stl. I have better pix somewhere, but can't locate them rat naw.
The bottom was key, no more scuppers drilled into a water trap!