Looks like Copper Mtn overnight is OK!
I was at Copper last weekend and saw three campers in the Alpine lot (one silver bullet camper and two Class C RV's). It was almost like summer there and these folks had their slides out and had set up for some Apre ski parties. It looked like they had spent the night because they had real close in parking.
I called Copper when I got home and the person in guest relations said people come up in RV's and spend the night all the time. I had him confirm that they actually allowed people to spend the night in the RV's and he confirmed that yes, they allow RV's and people are allowed to spend the night in the RV's. I wanted to make sure he understood the distiction between parking the RV in the lot vs staying in the RV in the lot. After asking the question three or four different ways, I'm convinced they allow an overnight stay in their Alpine lot.
Of course, the snow is all but gone so I cannot test this until November or later but trust me, I WILL test it and report back!
Traveling whenever possible with DW, 3 kids and "Tate" the mut dog. 1999 Minnie Winnie 3F430V