Brian: If you want to go with plywood, an alternative would be deck sealer, spar better, but you can by deck sealer pretty cheap especially 5 gal bucket. Do like I do for this process: take 1 to 3 gal. weed sprayer fill it with sealer and spray 3 coats both sides, letting dry between coats. Easy clean up some paint thinner and it cleans sprayer right up. popcorn The Truth is Out There (Yep It works)
