You said you were lookin' for ideas, well I've got a few...
1. a more esally worked heating system.
2.a few goal outlines
3. I notised that with Last Days, chain armor locks like a gas suit. perhaps you could work with that, as there are mods that allow you to craft chain armor
Wow, I really like this idea, but when you first spawn, you are in the sun. That violates rule 1 right? Lol jks. I might try this, probably not though, you need to find a really good cave system to survive.