I'm doing bagged lunches for 100 people, and am looking to use foil sandwich bags for the sammies. The catch is that the meetings are staggered over a 2 hour period. I was thinking of putting out the first round or two of sammies simply in the foil pouches, and pulling the last round out of an electric cambro. Any advice on these foil pouches? How long do they keep food warm/hot, and any input on "bun integrity"