I think your goal of showing the looseness of the gully was well met. Is it possible to downclimb this instead? It seems the rope induced rockfall would be more of a hazard than sketchy downclimbing.
It was a nasty gully. It could probably be downclimbed but it was really loose. Part of the problem was that the rocks were small and shifted so easily underfoot. We decided to rap because it felt safer even with the potential of party inflicted rockfall.