I know a group of guys that did a guided float like this and had a good bit of trouble from "local fellows". They had a group come into their camp and cause trouble and had a bullet hole appear in one of the beached boats one afternoon. They said that the local fellows considered it their territory and did not like outsiders taking their game.
This happened about ten years ago. It was about a week long hunt, but I don't know what river they floated. They all got nice trophy game but they all said that they would not ever do it again.