I don't check on their policies but do occasionally skin up. Think if you just skin you are on your on/ok, to go where ever. However, when they are blowing stuff (especially the bowl or back side) or things are "delicate" all over they will occasionally plant signs not to hike up the mountain. Skiing off the top when lift is closed, especially when there is lot of deposition and wind, I think you could really ruffle some feathers. Occasionally, we'll ski of the top to out of bounds to other buttes. We usually let patrol know that those tracks going out of the area are ours, this way they won't have to wonder about whether they will be doing a search later where they saw those tracks. They are usually pretty cool about this stuff especially when you can convey to them your understanding of locallized loading (and possible consequences...) and safe route traveling
On another note, when riding lifts I occasionally skin up high when the summit is closed (which sometimes is hard to figure out why....)--have got some great multi-turn pow runs doing that. Exercise a little common sense and stay out of their way, and I'm guessing you won't have any problems.
