Nejaminb, yes, you're right on the money, in my eyes.
I'm hoping that you and others will consider taking this too the extreme too, by using bass instead of balsa for the event! Except for maybe a few minor pieces, I coach bass construction. The pieces are definitely smaller and can be tough to work with, but the results speak for themselves: 4 wins at nats (2000, 2001, 2003, 2009) plus a 4th place (2006, though this one was almost all balsa). Maybe it was just the new event last season, but if you saw the B division results that RJM posted after nats last year, the first place entry beat #2 by close to 20% in the final score, which is pretty much a landslide. All I read about in this thread is balsa, balsa, balsa. I say wrong, wrong, wrong!
My main basswood source is northeasternscalelumber.com. Gussets in last year's design, for example, were 3/32" wide x 0.020" thick x 5/8" long. This was a tiny amount of mass that never failed!
I would consider using more balsa only if the calculated forces were low enough to do so, like in 2006. This was not the case last season with the compressive and tensile stresses significantly higher than on any of our national medal entries from the past. So, this just cemented us to bass, pun intended.
So, wait for the rules to come out, calculate out a few different designs, see what the stresses are, then choose your materials. You can actually start this by taking the node points I gave on last season's B division nationals winner and designing the materials for each piece such that the total mass of the wood used to interconnect them (with 7 interconnecting triangles) is about 2/3 of the total mass. I would like to tell the group what percent of this mass was used for the main compression pieces, but that would be giving away too much information, much like aia not including their 7th place C division photo in their gallery.