work for a skateboard deck? Ordinary 1" x
8" (or 12") wood? Plywood?


You surely need plywood and baltic birch would be a good place to
star. Probably 1/2".

The amount and direction of allowable bending is called compliance. If
you want certain characteristics of stiffness in one direction but
compliance in another you can take a lesson from the carbon fiber
industry.

If you made your own plywood from thin sheets of veener you could
align the grain all in one direction to have stiffness in one plane
and compliance in another. Or mostly all in one direction with a few
plys in an alternate direction for mostly stiff and lostly compliant
in each direction, etc.

Heck, maybe you should look into carbon fiber sheets or maybe even
fiberglass.