No matter the location, always leave a team member with your equipment.
At this late date, it will probably be "catch as catch can" for parking, IIRC, there's usually some parking available for tech and contingency along the shore south of the cruise ship docks and west of the Embarcadero, but I'm old and have CRS.
As Ol’ Curmudgeon stated above per parking for Tech & Contingency.
I park just west of the start and finish line area ( literally across the street). It’s a paid parking lot. I always park there at 7AM, day of Contingency and get a spot where I can visually see my truck from Contingency Row.
If the lot xrbaja mentioned is full there's another paid lot 2 blocks further south (turn left on Calle de las Brisas). It's fenced and there's an attendant; we've left vehicles unattended in there without problem but I knew we were taking a chance....
If you did your homework, you would have a hotel parking lot that is walled and secured which saves a lot of hassle. Another option is park the vehicle with all the stuff down where the fuel guys dispense and take a vehicle with nothing in it back up to park near contingency. There will folks around there for most of the day.