I would leave the crop as is, but I would burn in the section where the people are to make it less obtrusive -- the darker are would be balanced by the dark background on the right. The swimming duck will provide enough counterbalance to the main one. You can't go so dark so you can't see all the faces, so I might blur them some. Or maybe I would try cloning them out altogether.
Thanks, Alan. I had in fact already done as you suggest, but I can pull the sliders further to the left, giving this. I think cloning out the faces would be more trouble than it's worth (and I do rather like the human presence).
I'm reluctant to crop, as I can't see a way to do it without losing balance.