A cheap sheet of plastic, duck tape, a bucket, and her chairs will solve that. Suspend that sheet below her via taped to the chairs. Cut a hole in the center so everything can drain into the bucket below. For the rest of that "job" a spray bottle filled with lever anti-bacterial body wash and warm water. Use a back scrubber so you don't have to touch it. Spray and scrub it like you would an animal. I thought this up on the fly.