I will jump on the vacuum then freeze bandwagon. I know a number of people who do this for a variety of reasons. Getting a good vacuum on the package is key to minimizing moisture with freeze-dried foods, although living in a dry environment processing does help. There are many people who process their game the same way (vacuum bag then freeze), and in San Diego places like Fisherman's Processing has made a business out of doing this for the clients of the half-day to multi-day boats. I suppose you could also throw in a food grade desiccant package into each bag before you pull a vacuum and seal each bag of FD stuff.