I've used the Roy Robinson Poncho/Tarp Tent (8' x 5') over my hammock, and it gives adequate coverage. The bungee loops are a good idea. You don't really need hardware to attach the tarp to the prussics, so one figure 9 for the ridgeline ought to do you. Some day you'll probably want a bigger tarp, but this is a good startup solution, and it packs small. It will teach you to pay attention to wind direction and weather patterns, as well as landforms and protective vegetation. You'll be an ace at campsite selection.