According to this chart, San Francisco could service 10,000 people over over 10 hrs with 72 Porta Potties with a waiting line of 10 people. A little math gives us 173 for 24 hrs. The ad says that prices can be as low as $500/mo/unit for long term rental. That's only $1,038,000/yr. They spend well over that right now.
https://www.dailywire.com/news/san-francisco-has-spent-and-insane-amount-money-emily-zanotti
https://www.portapotty.net/