my friend and I are going backpacking in less than a week so I can't order an extra tarp for her. I have a superfly that I have used our two hammocks under numerous times between three trees. Neither of us at cordinaded enough to do bunk bed style. We are going to an area that has designated campsites so I am worried that we won't find the perfect three trees every time. Rain is in the extended forecast. I do have a paint tarp that I used before I got the superfly, but I am wondering if there are any CHEAP lightweight options that I can get at a box store. Anyone have any ideas?