A bit of hard stuff
I would use a little 1/16" birch plywood on the sides (in the middle) to add strength to the pants and use 1/16" balsa sheet to make the pant sides. Also, use something like a 1/4" (all depending on the thickness of the pant) balsa stick for the LE and TE of the pants. Then just sand them to a smooth contour.
This should stand up to most hard landings.
-Q.