Wow! That is a deal especially this early in the year.
We took the girls to Legoland in Carlsbad, Cal when it first opened. So "first" that a couple of the rides weren't even done yet. DD2 was too small to go on the rollercoaster but we were already in line when we found out so we said we'd peel her and an adult out at the loading zone. Somehow that didn't happen. At the end they had a camera to snap pictures of the riders, bottom of a big drop. DD1 looked horrified. DD2 had a HUGE smile on her face. She still loves roller coasters at nearly 26.
I'd go with the 2x3. CPs are hard to bend and if you don't have a broody hen to take over, you need to raise the cave as the chicks grow. That is usually done by bending the support.
And you have that often in Woodland?

No, no one wants to plow 2' of snow.