Ok, so here's a list of men missing from Sonoma County from 1986 to 2012. 10 out of the 16 people listed on NamUs fit that description, although I've excluded one (Robin Reed) because of the circumstances. The distances listed are from Shiloh Park to the town/city these people went missing from.
Jesus Madrigal - Dec'2012, Santa Rosa, 8.1 miles away
John Farfan - Nov'2012, Santa Rosa, 8.1 miles away
Curtis Sloan - Jan'2011, Santa Rosa, 8.1 miles away
Donald Still - June'2007, Guerneville, 17.6 miles away
Benjamin Barros - May'2004, Cotati, 15.9 miles away
Timothy Criss - Oct'2006. NamUs says he went missing from Santa Rosa (8.1 miles away) but the circumstances listed aren't too clear ... it says he went to help his brother move to New Mexico, Criss left a note saying he was going back to California, then it says he was heading to Mexico for a fling.
Dennis Harrington - July'1995, 21.8 miles away (Monte Rio)
Michael Troyer - Nov'1994, 32.5 miles away (Duncan's Landing State Park)
Anthony Horner - Feb'1989, 8.1 miles away (Santa Rosa)
I was going to list Jason Kyles, who was last seen by a biker in early February, chanting and walking around naked in in Annadel Park. But he doesn't fit. One, he went missing only 10 months ago. And two, he was last seen naked, and his pants and shoes have since been recovered and the tags had been torn off. Besides, I think he'd be fairly easy to rule out (depending on what bones were recovered) because he was 6'6.
It sounds like the poor guy had a mental health crisis and somehow died in Annadel Park.
I also excluded Robin Reed, who went missing in January 1995 from Petaluma (24.5 miles away). It says he was last seen wearing tan pants, which fits the description, but all indications are that he killed himself by jumping off the Golden Gate Bridge.