You could make all the hatches into a single hatch, connected by sections of deck. I combined two companionways, with the capstan between them, and a skylight into a single access hatch, but under the bow and stern pivot guns, are flush deck openings. The main hatch IS the main hatch.
On my Pride model no scale hatch is large enough to get a hand through, so all the hatches will be "flush deck hatches."