I expect that A-Basin has the lots included in their permit from the NF, plow and maintain any place you'd be able to park, and thus will have precedence over general NF rules. Its been my understanding they let folks park RVs in the upper lots overnight, at least. I once camped out with a buddy in an RV up there during a good storm, got up the next morning walked over to the lodge and, with a cup of coffee in my hand, had the pleasure of watching 20 lb charges tossed into the Professor from a CDOT helicopter before they opened the Pass. The only bummer was that the Prof. didn't run - that would've been a kick...
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse