I have never hunted that area ... best to go scout and talk to some locals or the game department in that area. Was hoping someone who has would get you into some general areas.
However, I did gather some info about 13 years ago ... and it was more for spring hunting, but it may help you get started ...
Okanagon Merriams:
old Hi-97 11.5 mi North of Brewster, then west on Chiliwist Creek Rd to Forest Service land
-west side of Loup Loop Pass Hi-20 between Okanagon & Twisp (between Wolf Canyon and Hi-20 best)
-between Brewster and Okanagon – up Paradise Hill Rd to Rat Lake Rd, past lake – or to where Paradise Hill Rd becomes Benson Creek Rd to Okanagon Natl Forest
-Box Canyon Rd, North to Ski Lodge Rd (west of Hi-97)
Good luck ....