The people that I know park on the Banks Lowman Hwy turnout at the road/trailhead to Deadwood. Course you could come in from Lowman thru Bear Valley. Hope this helps.
Im also in cascade on weekends and i just drive as far as i can into warm lake... then the road ends everyone parks and unloads.! just ride into deadwood from there. There calling for a ton of pow on west mountain! sundays going to be nuts!!