George, sounds like a good idea. However, if I were a boat builder, I think I would use the honeycomb fiberglass construction that is frequently used on the sterns of powerboats. It's extremely strong, lightweight, and you never have to worry about it absorbing moisture. The use of wood for a boat core, IMO, is archaic. When will sailboat builders get their heads out of the sands of tradition?
When I purchased my Morgan 33 O.I. it had moisture in an area of the cabin top core. I had it drilled and filled, and thus far, after three years, no moisture there. However, just this past summer, during a heavy rain, water began seeping into the cabin overhead and dripping through a hole over the quarter berth, soaking the cushion. I was able to dry the cushion OK, but thus far have not found the leak source. I found several toe rail screws that had not been sealed, and sealed them with 5200. Sometimes it can be difficult to find a leak source.