Suggest you go in an off month. We went in October and had the camp site practically to ourselves. It fits about 100 people, and we were just our group of about 15 and then two or three others.
Be careful in what off-month you go. February and March are the driest. Some months are impassable or closed due to very deep mud/slides.
During some of the wetter months even mules will give up, and are left abandoned.