Try to pack soft bags, you can cram more stuff into a vehicle in odd spaces. If you can, see if the group has soft ski bags. If they all have hard shells, tougher.
We just got back from Denver for a week at Steamboat/Copper and Suburbans were going for $1600, Subarus were $700. There were no SUV's in the upgrade / choose your own lots at Hertz. We took a big sedan for $350, checked that were Mud & Snow tires on it, and grabbed some chains/gloves/spiders at Walmart. If everyone is an adult, and comfortable driving on snow, you could see if two cars work.
While its true CDOT might not let sedans go up/down mountain under some conditions, its also generally the case that if that's happening the road is going to be shut to everyone pretty soon, even if they are driving a tank. Hwy 40 between Steamboat and Kremmling had a total shutdown on Friday in the Rabbit Ears area, and no one could get through until it was reopened.
We're on the West Coast now and I've come around to the view that I'll take a connection (likely in LAX, PHX) to get into Eagle, Pitkin, or Hayden to be on the other side of the tunnel. Air travel delays usually mean we're in the airport (lounge) or in a hotel overnight. Road travel delays mean we're bumming on I70, which is worse.