Silly question...Why wouldn't you vac pack it warm (read-not HOT), and then ice bath it? As the meat/food product cools, I would think it will create a better vacuum in the package. Fill a water bottle with hot water, empty it, cap it and see what happens. Just a thought.
2 18" WSM's (L&DE), 1 22" WSM (AA), Chargriller Pro offset, WGA, SJS, SJ, Char Broil charcoal grill