Brian:

Since she was already crawling in the snow with the skis in front of her, why would laying on the skis make her colder?

If she had an external framed backpack, she could have bridged the skis with the backpack frame laced to the bindings so the cordage was not on the bottom of the skis, and lay on the frame which would have kept more of her body out of the snow.

Bountyhunter