I am in the stage of purchasing materials for a permanent blind that will be located on dry land, but close to a river. It looks like this area will flood, but with the elevation of the blind usually only the 4x4's will go under water. For guys that have been here and done that: How far should the 4x4's go into the ground? Use concrete? Did you anchor the blind to any surroundings? I have seen some very large screw in anchor systems that could accompany the 4x4's, is this a good idea or over kill? Any other advice will be welcomed.