4th of july without a radio?
Nope, a working VHF radio is not required equipment on any private vessels to 20 meters. Oddly, it does make the list of recommended equipment along with a cell phone!! Having been to one of these affairs, it is more important to have a multi-million candlepower aircraft landing light to blind the damn stinkpot driver with his spotlights ablaze and you leading him into the breakwater becuse you are blinded!!!
Use normal traffic conventions, have working nav lights, and, audio and visual distress signalling devices (as CG required). If you don''t feel comfortable with just a cell phone, I am sure there are a number of skippers in the harbor who would lend you a handheld.
If possible, go in the daylight hours with a GPS and establish a track to the viewing area. The first time out of the breakwater at night is very intimidating. Shore lights wash out nearly all navaids in some locations. Enjoy the show.