Please continue!
...With such a historic past, I started wondering if the mission grounds have ever been detected....
....It's been a while since I've been there, but if I recall correctly there is also a large grassy area in front of the mission at San Juan Bautista. I would assume that this area along with other areas around the missions may hold some history that could be found. ...
.......Yes, yes, I fully realize that these are historic landmarks and there are a plethora of laws / rules / regulations against such activities...