Anybody have any experience with using dry ice in coolers? If so: Is the carbonation/gas thing really an issue for food? If so, is plastic (like a vacuum seal bag or store packaging) sufficient barrier? Any experience with using dry ice to keep an ice-only cooler vs dry ice in each cooler? I ask because of the potential of turning coolers into freezers, which isn't really what I'm going for, other than keeping ice frozen. I don't want to be dealing with defrosting, I just want stuff fridge-temp to start cooking with. TIA!