I have used the type of rainfly in question as a tarp tent for ground sleeping, it worked but was not ideal. I had to use the pole as the ridgeline, because as othrrs have mentioned it won't pitch taught otherwise. I had to guyout with shockcord all the way around to get a proper pitch and it was barely big enough for a single person to sleep on the ground. I doubt it would work well for a hammock because of it's short ridgeline. However as Jeff says "impossible only takes longer" give it a try and let us know what your experience is.
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