1) Load the COLD AND DARK setting from BASIC STATES
2) The Battery (BAT) Switch will already be ON, so rotate the Standby (STBY) POWER Selector to AUTO
3) Save the new state as DEFAULT in the CUSTOM STATES.

I know this isn't a true Cold and Dark setting, but it's the closest I can get to it because I can't find as way to access the CDU's menu, without first turning the Standby (STBY) POWER Selector to AUTO, or BAT. I looked through the DEFAULT.cfg that I created doing the above, but I can't find (or figure out) the entry that is the Standby (STBY) POWER Selector in it. I assumed it would be listed under O07, because of this - O07. BATTERY/STANDBY CONTROL PANEL (from the CS757CAPTAINIII_MANUAL_PART2.pdf), but I can only find 3 entries, and they all matched in the COLD AND DARK.cfg, and the DEFAULT.cfg files  :(