Call a tree service (Ed Cook is the largest) and see if they will be in Glenbook in the next couple of days. They might grab it for you for little cost. I live in South Lake Tahoe and rarely fly near my house. I'm guessing the avoidance didn't work?
I know this advice is a little too late, but, I too live in the Sierras - frickin' trees everywhere. As I approach trees I tilt the camera down slightly - say15-20°. And I ask myself, "Can I see the 'tip-tops' of the trees?" If you can see the tips, then you are flying above them. If not, then prepare to call a tree service - as suggested above. Good luck - report back if you successfully recover the drone.
If you reset your gimbal straight ahead, then anything below the horizon (center of screen) will be below the drone. I allow for some extra space, but I have seen some people get what I would call WAY too close and still clear obstacles.