Here's a crazy idea.
Why not, prior to Kickoff, release a "Cut List"? Doesn't have to be final size, but I could see something like this:
Element 1 (<=1):
- 5" x 5" wood beam, 3' long, QTY 1
- 3/4" plywood, 3' long by 1.5' wide, QTY 1
Element 2 (<=1):
- 3/4" plywood, 3' long by 1.5' wide, QTY 1
- 3' long 1.5" x 1.5" wood beam, QTY 2
Element 3 (<=5):
(list of parts for defense base)
[remaining elements of field]
You get the idea. Doesn't have to be final size, or have any funny angles included, but should be, if cut, a "kit" that will allow teams to take an educated guess as to what they'll want to build, and the approximate size. For example, if I saw something saying "<=5", I'd take a guess and say "I think I need to build a couple of these, let me look at the list for that". And for stuff with a "common" piece, I'd probably cut a bunch of those pieces.
Then, when Kickoff comes out, all FIRST has to do is include one extra list with the Manual:
Element 1 = Rock Wall, pg X
Element 2 = Rough Terrain, pg Y
Element 3 = Defense Base, pg Z
[...]
Then everybody can get their pre-cut "kits" and assemble.
Still doesn't solve the nuisance of "hey, who gave us bad team-build materials" but should get teams to that point faster.