This is an aerial photo of one of those green spaces that was on track
Yeah... the longest practical surface distance there is 900 feet, and if you exceed that by 300 feet either way, you're probably hitting someone. Were I to be the authority, I would be very skeptical that most recreational pilots flying an Arrow could tuck it into 900 feet over several storey buildings without hitting something. And that presumes that you were at just the right place along your route when it quit to set up into there. A pilot thinking that meets the requirement for a safe spot in an emergency is really hoping a lot! I certainly would never consider that a safe flight for me to fly.