Oh! I remember the shape now
Hey, I didn't know Manchester had so many palm trees!
how about doing something like a top cover that AHE makes for WB's but combining it into a tarp? head and foot end of the tarp would attach to the suspension via mitton hooks, the shelf side of the WB would have a pocket (on the tarp) where you would run the side pull out trough on the hammock. 2 prusiks would be added or maybe one on the shelf side to add tension to the tarp on that side. on the door side you would have one or two guide lines depending for the coverage you want. you could cater the dimensions for the most come weather you'll be in and or guidelines.