I've posted pictures in the past of the mods I did where I put holes in the bottom of the bags for the suspension to go though.
My son regularly uses the modified bivy and patrol bag as a "pea pod" type system in the cold weather. He's a skinny teenager, so he can zip it up around him with being in the hammock. With me, I've uses the combo as a UQ with good results.
I modified one of the bivy covers for a wet weather shielf for my Wilderness logics UQ.
Plans in the works to take a patrol bag and mod it to a straight UQ.
Goretex bivy and patrol bag compress up pretty small, but the heavy weight bag for the really cold Wx is too heavy I would think.
I used the whole system with a military CCF ground pad in subzero as a ground dweller in the past, but would not use it for the hammock.
Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem.
Ronald Reagan, President of the United States