There's a little park with a decent sized parking lot down at the north end (I think) in the Cannery Row area, where the Ferrari club has a meeting every year before the Historics. I'm not sure it would fit 50 +/- cars though.
www.montereybayinn.com is the hotel.
If you use google maps for 242 Cannery Row, Monterey, CA, then go to an aerial view, you will see the parking lot is right on the water near the hotel with a large grassy area.