Has anyone actually monitored activity at the motorcycle park and have frequencies in use there? There's a repeater, but it doesn't get out very well, apparently.
Can not really help you much, I see there is a Parks repeater licensed on Carnegie Ridge (16 miles SW of Tracy) on 855.7375. I do notice it is only at 1,500 feet however. You most likely already have this info. There are a couple of real experts in Livermore than may show up and have more info
It is very local to the area from a Livermore perspective. Folks in the nearby Central Valley may have a better chance as I can't hear anything (or key it up).
I'll have to take a drive one of these days and post back.