Thanks to all the great ideas on many topics. Sharing is caring. Here is what we did to keep our shins from baking. Compact, cheap and portable. The board is 1/4" cement board cut from a 3' x 5' piece (Home Depot $12). The support legs are spring clamps (Home Depot $0.99 ea.). Cut the board by scoring with a utility knife as deep as you can along a straight edge. Then snap it off.

You can also see our temporary roof support as we're getting ready for 4-7" of snow overnight.