Wow, huge job there, looking good!
As far as the wood goes, perhaps you might want to consider a foam or composite core material instead.
Aircraft Spruce (
http://www.aircraftspruce.com/index.html) sells a lot of different kinds. If you're planning on keeping the boat for a while, even though it is a bit more expensive, might be a better alternative than wood.
I have some experience with composite cores for experimental (home built) aircraft, and they are VERY strong. If I ever need to replace any wood stringers on my V it will definately be with a foam core.