Wouldn't running a normal "cold-wall" type chest freezer at -30 degrees just cause the inside of it to get smaller and smaller due to massive ice buildup on the walls, or would it be about the same as a 0 degree freezer? Or were these the kind with a fan inside and auto-defrost?
What's the relationship between wall temperature and frost build up? I don't think its too bad with chest type as the outside air infiltration is minimal compared to front load type.
The water removal from contents would be reduced, no? The lower temperature reduces vapor pressure/sublimation rate. This is why its said that ultra cold freezing reduces freezer-burn. Granted, not sure how effective this is at -30F