For the Tunnel, look for signs of comings and goings, foot prints, disturbed dirt.... if its a regularly used spot, these should be appearent. Bring a bright flashlight (or two) and a couple candy bars for peace making in case you disturb a lightfooted indian...

I would assume its there but can't see it, be careful of poison oak. I have been tempted with a few places here in Santa Cruz in the parks but I get that pretty good, I watch for that itch causing plant every where I go...

You have some nice spots and privacy to not be disturbed while taking pictures. Can't wait to see what you come back with.