We have a heavy plastic tarp w/ grommets. Brown on one side, Pewter on the other side. Can I use this to cover the top of the run to provide more shade? Should I put the pewter side out or in? I don't want to make it hotter. I ordered a mesh shade tarp, but it is not here yet and we will be out of town for the week...and the entire week is supposed to be high 90's.