Tides will complicate night flying, but something may be possible. I'm a little skeptical given my past experiences, but there is always a chance. The tides will work for the festival, but the water will be there like always:
Tide forecasts (rounded) and dawn/dusk:
Wednesday: 3:15 AM high 0.9 ft; 11:30 low 0.2 ft; 7:10 pm high 1 ft; Dawn 7:14, dusk 6:10
Thursday: 1 AM low 0.7 ft; 5:10 AM high 0.7 ft; Noon low 0.4 ft; 6:55 high 0.9 ft; Dawn 7:13, dusk 6:11
Friday: 2:AM low 0.5 ft; 7:30 AM high 0.7 ft; 12:20 low 0.6 ft; 6:36 high 0.9 ft; Dawn 7:13, dusk 6:12
Saturday: 2:30 AM low 0.3 ft; 6:00 PM high 0.9ft; Dawn 7:12, dusk 6:13
Sunday: low 3:00 0 ft; high 1:30 0.9 ft; Dawn 7:12, dusk:6:13
Also a note for the future: SPI has been soliciting proposals to develop the flats, driven by their "Convention and Visitor’s Advisory Board". The Sierra Club has been fighting it because of creatures and habitat, some locals have been fighting it since it's the only bay-side public beach. The city's published goal is to encourage profitable water sports in the bay (kayaking, wind-surfing, and personal watercraft, including rental businesses), and they want bids for developments accommodating 7,000 spectators, at least 2000 covered amphitheater-style bay-facing seats, plus boardwalks with shops, and places to launch watercraft. The plan wants to start building within three years. So enjoy the flats while they last. :-(