I hunted Manistee National Forest last year and had the same experience. We hiked and drove all over the place and the only gobble we got was from a few birds we looped around on that we saw in some guy's yard that backed up to public land. Hunting the big woods is fun and beautiful but I felt like we were looking for a needle in a haystack. I talked to a few DNR guys in the area and they said most of the birds will be on private or close to private. Certainly they are in the timber too but if you are playing the odds I would be looking at public that backs up to private (especially ag land). We had wonderful camping and hiking but I'm not in a hurry to head back there for Turkey (I probably will again though lol).