The WMA's here in California get hit pretty hard each season; just from my observations they are getting worked over pretty hard this year. Like any kind of hunting, you will get the best results by scouting the area(s) and trying whatever tactics your situation dictates to throw at the birds (call, decoy - etc).
Are there gobblers @ Cache Creek? Sure... Then again, there is a HUGE population on the U.C. Berkeley university campus, near downtown Berkeley - which I mention to illustrate how good the turkey population is here in California!
Here are my suggestions for Cache Creek:
• scout the area best you can; bring binoculars and glass too...
• try to get 2 days in; 1 to scout and 1 to make the kill, works great for unknown real estate
• be extremely careful @ cache creek, like many places, there is a TON of rattlesnakes there. Cache creek seems to have a "higher than average" rattlesnake population from what I've seen. I got 'buzzed' at a dozen times easily by snakes last spring turkey.
• be mindful of the granola eating hikers and horse riders there, there is a lot of them
• try your best to get as far back into the back country as you can hike; true to form as with many public WMA land, the weekend warrior hunters tend to bust birds and push them around alot there.
If you haven't got a map, get the map online as well. Cache creek is big and is also near Payne Ranch, a map will be key to knowing the layout of the land - there is some serious terrain in some portions there.
Good luck boss!!
"Any day my guns don't collect dust or sit in the gun safe is a good day."