Don't mean to rain on your parade since it seems like such a great use of a piece of gear, especially if you happen to already own one... but seems like you're opening up a can of worms there. Not sure if it was your idea or the manufacturers, but they stamp every rope wrench "not for primary life support". I made myself a wooden one, and own both the early metal and second gen RW's. Since it has no load rating stamped on it, it has no place in a commercial environment as a rigging tool, even for light rigging. I'm sure that even by your own manufacturers standards, using the RW in this way is outside of the scope of its original design. Further to that, encouraging people to use a life support device (even a non primary life support device) as a rigging tool seems like an idea which could easily come back to bite you on the ass.
I have a light rigging setup I regularly use for situations where I need rapid lifting. I use it mainly for situations where you end up with no high point high enough to clear an obstacle, so you need to snatch the piece faster than what you could by means of a friction drum/grcs. I use a 1/2"rope, up to a ratchetting friction pulley up high in the tree, and down to a pulley tied off at the base as a redirect so the groundies can make effective use of their pulling power. I use a ronstan ratchetting pulley intended for sail boat use, it's load rated and offers no resistance on the "up" pull, but up to 10:1 holding power on the down side thanks to the machined grooved sheave. Harken makes a similar product. They come in a range of diameters and load ratings.
With the redirect at the base, 3 or 4 guys can all be in line and pulling effectively on the rope to achieve lift very quickly. once the piece has been lifted/swung in, even one man can easily manage the lower off with hand holding only on sections up to the 400-500lb range.
