Try vaccuum packing to remove the extra air. A food sealer, maybe? ... 
Hey, that's not a bad idea.  I picked up a food sealer just for sealing up some non-food type items and I know it's pretty good at getting every little bit of air out*.  I'll have to give it a shot, thanks.
* - Why do I say this?  Tried to vacuum seal some backup items (extra bandanna, small knife, small flashlight, etc. along with a couple of individually packaged 
hand wipes.  Big mistake, the packages burst and the liquid went everywhere (and they were 
scented wipes, which made everything nice and smelly.