Steve,
I don't think I ever kept any photos from the build of 'Eric', but if I did, God only knows where they'd be now....
Essentially, where the plans showed bulkheads with lightening holes drilled in them, we built diagonally braced trussed frames. Where the plan showed 6mm, we used 5mm. For 5mm we used 4mm and so on. The re-inforcing under the beam trays was honeycomb paper and epoxy sheet (I've still got some in my garage

) and the longitudinals in the bows were balsa! Basically we tried to think lightness at every opportunity.
The deck beams were all shaved and shaped and were braced to each other before the decks went on. We did away with the gunwhale reinforcing on the tramp area of each hull and instead of aluminium track, we projected the deck out over the edge, re-inforced it from underneath, then drilled it to take the tramp lacing.
The area where we couldn't really save any weight was the centreboard boxes/main bulkhead re-inforcing just by the main beam.
The beam trays were made to an approximate shape for the beams and then finally shaped using microballoons and epoxy painted in and then the beams bolted in place with waxed polythene to protect them.
Once it all came together, even without the rig, if you lifted one bow the other followed after just a cm or so of movement!
Ah, how I miss that boat.....