Private/alternative prom at public school

We did it last year when my son was a Junior. No advertising or ticket sales at the school, and our Juniors/Seniors do not not normally have to buy a ticket since it's their prom and they fund raise as freshmen and sophomores to cover these costs. Anyhoo for our private prom they did have to pay 30 dollars each. Now there was a social media blitz about the tickets and invites. We also had tickets gifted to any student who needed assistance. Prom dresses were donated. More students attended this outdoor private prom then probably would have attended the regular prom. We went out of way as parents to make sure every junior and senior was aware of this opportunity. One family even donated all the boutineers and corsages. We only have about 60 graduates each year though so it's very easy to include everyone in a private setting.