We're building a covered run next to our coop; we need it covered because there is no shade in our yard. We have 1/2 inch plywood on top, at a pitched angle (like a lean-to). We are in SD and get a lot of strong winds. We were thinking about regular shingles, but the roofing nails would protrude through the plywood; we really don't want anyone bumping their head on nails when they're in the run. Any suggestions as to what would be the easiest to install, yet decent quality material to roof it with?