Duh. C and D are going to be supported either with bamboo rods or with 2x2s and probably with stapes and tape. I think I might try this foil tape I have seen but I will take suggestions. I know packing doesn't hold up under the sun or wind. I wonder if there is a glue I could use, or caulking in the seems? I am mostly worried about the wind. We get some really fierce ones where I am located and nearly all fall and spring. I think the wind comes off the road, down into the pond and then up the bank into our field as it heads onward across the road to the open field across the street. We really need more evergreen barriers to break it up a bit. The chickens around here need anchors or flight training and homing beacons.
I have found rolling the tarp edge around scrap wood and nailing works great