Of course you can rig a pully system to use the righting bag. I prefer to have as little complication in a system that needs to work every time. I don't want to have to mess with fouled pulleys when I am trying to quickly right my boat.

When I've used them in the past, I jsut put the line holding the bag over my shoulder, stood out like I would on a smaller cat while holding the righting line. When I stood out the bag came out of the water. Since I was wearing my PFD the padding distributed the weight of the bag.