I have used the gallon sized vac bags for dry curing bacon. The air (or lack of air) will not harm the process. Just make sure that if the air causes the liquid to pool to one side, be sure to rotate the bag for even coverage. The vac-pac keeps the bellies surrounded with the liquid, almost eliminating the need to rotate. But always rotate for equal dispersion of the curing agents.
Humphrey's DownEast Beast W/BBQ Guru