i think the hatches on the 5.0 should be like the 5.2

1 behind the aft beam

and 1 behind the main beam

your early series of photos show what look to be the inside of the hull forward of the beam, presumably your lowered your camera through a hatch forward of the beam

your later photos also seem to show a hatch forward of the beam

the factory presumably doesn't put hatches there as it is 1 of most highly stressed hull areas. there are huge loads in all directions from those long unsupported bows which is why when you see photos of collapsed cats it is usually the bows that have snapped off just forward of the main beam

you might get away with simply monitoring that area very closely or it might be better to remove the non-standard hatches there and glass in the holes