You would have to be seriously unlucky to die or become stuck with in a resort, especially given that Ski Patrol sweep runs at the end of the day, you've also got Groomers and maintence staff working on the mountain all night, finally buildings and lift stations are left unlocked in case you needed emergency shelter.
I worked for a year in mountain operations for a major North American resort, working closely with Ski Patrol. Deaths nearly always came from collisions with objects and head/neck injuries. In the two years I was there, there wasn't once a case of somebody getting stuck within the resort itself, or dying.
The majority of deaths tended to be where people had ventured into the backcountry unprepared. I remember one being that of a Japanese man who went completely off on his own, no equipment and walked into a lake, he was found dead just a few feet from it. That is venturing outside of the resort though, where you should have proper equipment and knowledge.
Having a pack full of everything really isn't necessary for resort riding. If clothing is a major concern then I'd say that you should be somewhat dressed for the conditions before you leave the house. If its really into the negative temperatures, then it usually isn't much fun to go Skiing anyway, that's certainly what I found when it drops to -26.