[Stepheninky]

I have not made my own kraut to can before but with wines you have to also wait till it is fully fermented because if not it can explode the bottle with the pressure or bust the seal, so I am guessing that is why it says fermentation must be finished. We used to use those big bouncy balloons attached to the top of a 5 gal glass water bottle to do wines. the balloon will fill up with gas from the fermenting and then go down as it finishes when the balloon went flat we would bottle. Just trying to give you some ideals to go with.

use a double layer of plastic/saran type wrap, pull tight
and secure with a rubber band,, This would probably do the trick and act like a vapor lock, meaning if too much gas builds up it can escape out, but should keep anything else from getting in. It should completely ferment in the fridge in about 3-4 weeks at which time you could probably can it without any problems.

There are German crocks that do basically the same as the setup above would do.

Anyways, If I were to try it that is how I would probably go about it.

There are so many Amish and Minonites around here I usually just buy it already in canning jars from them. If you get out in the country side and visit the groups around here the prices are not too bad. I can buy corn, cabbage, broccoli, and many other veggies from them cheaper than I could grow it myself and that leaves me more room for other veggies in my garden.