Going further, how about 100% redwood? It seems tougher than I expected, and it cut cleaner than the fir.

: This is what's available, and I'll be having strips cut tomorrow
: morning. The redwood is nice heartwood, and both have vertical
: grain. My only concerns are whether the redwood has enough
: strength where the first 3/8 in. lip strip will join the taller
: stripts, and then the whole thing with a tension curve with the
: skin sewn up to it.

: Probably all very fine, but, with zero firsthand exposure to
: others' work to draw from, I'd like to be sure. Thanks!