Yes, I have seen the same info you have on CA snow parks. Key is knowing which allow the overnight parking.
Can confirm based on last weekend that you can park and sleep in vehicle at Carson Pass and Meiss Meadow. Meiss Meadow is where you would want to stay, further off the highway and just yards down the road from Carson Pass.
Can also confirm Hope Valley does not allow parking from 7PM to 7AM, much less sleeping in your vehicle. Sign says you will be towed and it is by local ordinance.