For shooters to travel to an out-of-the-way location, you really need at least two courses, 25 targets or more on each. In 4 acres, you'll only get 5-7 targets out. Remember, the shooters must be able to retireve their arrows and score the shots without being in danger from shooters at another target. Add in camping areas, where people can put tents, and parking, and a good minimum is 1 acre per target, everything considered. The best thing is to go to a couple of shoots that are well run and really watch the details. Like anything, if a shoot is done right, it seems effortless, but is far from it.