Carld, just a thought, the bags my dog's food comes in are resealable (ziploc type) and are made of a very thick plastic - sure, they got a pic of an Australian shepperd on them, but hey, that just gives your divers something to look at!
The brand is Nutrience and you can get them in several sizes. If you got kids, you can probably even pawn the contents off on them without them noticing - my kid likes to snack on a few ocasionally as a reminder of how good his life is in comparison to the dogs!