It will be held at a private residence in the Del Mar Country Club. The most likely place for a rally/protest appears to be right in front of the main entrance at the intersection of San Dieguito Road and Camino Santa Fe.
The event is listed as a reception/dinner. So, he would be expected to arrive in the late afternoon or early evening.
There is some room to park along San Dieguito Road in the dirt. In case there is not enough parking you may want to carpool or be prepared to park somewhere else and use Uber or Lyft to get to the Country Club.