Yeah, I wasn't considering real Bomar hatches. Inspection plates is what they call what I had in mind:
http://www.foreandaftmarine.com/INSPECTIONPLATESBECKSEN.htm
http://www.foreandaftmarine.com/INSPECTIONPLATESBOWMAR.htm
I am thinking about using these for the seats, foredeck, and aft bulkhead.
Anyone have any they like?
(disclaimer: I have no affinity for, or affiliation with, Fore and Aft Marine; they just came up first in the google search.)