This is an excellent idea: it would work well with a solar shower or camp shower too such as this one sold by Sea to Summit which weighs about 100 grams (if you ditch the stuff sack). I find two 1300 ml billies of cold water (add FIRST!) + 2 of boiling water gives a perfect shower in the woods: http://www.seatosummit.com/product/?item=Pocket+Shower&o1=0&o2=0&o3=195
The idea would also work well when you need to hoist a deer carcass from a tree to ‘set’ overnight, or etc. This is a difficult enough job for one, but a 2 to 1 mechanical advantage would make it a lot easier. Using a Spanish Windlass also makes the job a lot easier.