Erice,
What kind of problems are you imagining for the inspection hatch? I already poked my boney butt through one on the opposite hull about a year ago, but that was an easy replacement.

Outside is glassed over with at least three layers of 60oz biaxial cloth all over & up to 6 or seven around some of the corner areas. Next up I'll be laying a similar mess on the inside corners.
http://www.flickr.com/photos/12713306@N02/6024347439