The easiest place to meet is right on the border on the last trolly spot. This is what it looks like on Google maps:
A view of the McDonalds Trolly Station crossing the bridge from Plaza de las Americas towards the border point of entry
Simply google “San Ysidro Border” to get directions. If you are driving to the border, there are multiple parking lots that charge anywhere from $5 to $15 per night in the US side of the border. If you are planning to cross to Tijuana with your car, there are multiple safe parking lots that are cheaper per night.
I will be there holding a Tijuana Adventure sign for an even easier and faster meeting.