I have seen some while hunting deer. Had a couple of flocks run across in front of the truck while driving to and from hunting spots. I enter the NF coming up from upper lake, I forget the highway. It is the main road that runs from Clear lake up through the NF and down to Lake Pilsbury. There are some meadows and oak ridges through there as you are heading into the NF. You'll need a map though as there are a few pockets of private land to watch out for near the start of the NF. I went up last year on the last weekend of turkey season and ended up getting rained out hard and didn't hear or see a thing. If I go back up, I'll stick to the lower elevation on the south side that overlooks Clear lake. Keep in mind I am a NEW turkey hunter so don't take my word for much.
I'm sure there are better places but this is just where I have seen them in the past so I would probably go there if I go back. I'm sure others will have much better spots. The rangers say that there is not a large population there but it is increasing every year. I usually camp in the Deer Valley camp ground and then I head south from there.
Besides double canyon, which you already know about. The only other place I know of that has birds is Lake Pillsbury and I have been up there several times and never seen a thing. From what I understand they around there. That whole road from upperlake to pillsbury I haven't seen a thing after the first couple of mile, but potentially good looking area. By plane the east side of the forest looks more like rolling oaks and the west is more dense forest, both good habitat, but I prefer the oaks. Lots of area and I am sure there are lots of birds. North, I hear Covelo is good and someone told me of a ridge that is loaded with birds, let me see if I have the name. I get back to you.
I have hunted estel ridge for deer alot and have never seen a turkey up there I have herd that there was turkey there from post like this but never seen them. amy be I ant looking for them at deer season or maybe they go lower at that time of year.