Amanda has a tarp for sale that is ready to go. It is her 10X12 Cathedral Cat Tarp that has 4 tieouts on each side so that you can close in the ends. $120 plus shipping to whoever wants it. Also it comes without the seams sealed, so you will need to do that when you get it.
p.s. You can see more pics on her page (thepreacherswife) or mine I think