It's actually devilishly hard to strap plywood to a roof rack in a way that it won't take off in the wind (you're essentially turning your car into a giant kite

It's actually devilishly hard to strap plywood to a roof rack in a way that it won't take off in the wind (you're essentially turning your car into a giant kite) but also won't warp. It can be done.. but it's hard.