I know we're talking theoretical optimums here, but: don't put your SSDs in the freezer. Water ingress because of condensation will kill your data much quicker than NAND bit rot at room temperature.
Re-freezing is also critical, the container should contain no humid air when it goes into the freezer, because the water will condense and freeze as the container cools. A tightly wrapped bag, desiccant and/or purging the container with dry gas would prevent that.
Color changing desiccant is a good idea to monitor it.
There are ways to keep water out of frozen/re-frozen items, of course, but if you mess up you have water everywhere.