I still think spending effort on an amphitheatre is not gonna be rewarding enough to warrant the effort.
Simply due to the fact that use is not guaranteed endlessly, it takes up space, and won't necessarily serve the community as a whole, due to the simple fact that those putting on plays will want to make people pay for the experience, and want dorrsmen, etc., and it'll just give opportunity for more anger and tension and flaming.
Just set up a show in Hydlaa Plaza, and let people use the large plaza steps as a seating area.