I still think the shooting happened in the river on a gravel bar. You can’t put a fence on a gravel bar. You can, but it will wash away.
The floaters have a right to be in the river and any gravel bar in the river.
I still think putting game cameras or live web cams and telling the floaters about them, would scare many floaters away that might think about using “the facilities” on that gravel bar.
I don’t think that the shooting occurred on the gravel bar. The men left to urinate in the woods on private property. That’s why the argument wasn’t in front of everyone. I am certainly not defending the guy, but I have seen signs in Arizona that say, Trespassers will be shot.