I was going through some clearance items at the REI store and found a Kelty Trail Dome 6 Footprint on sale for $.03. I do not need a footprint but for 3 cents I could not pass it up. Being a newbie to hammocking and not really a backpacker I am not familiar with 1800 mm PU coated nylon taffeta - is this water proof can I use this as a tarp? its 9x9 and I was thinking of adding a few tie outs to make a backup tarp. I am mostly a car camper/canoe so I am not concerned about weight. Any drawbacks to using this as a tarp?