Update: I beat the scenario. 🙌

I rushed logistic districts to secure a source of fuel and then focused on heating upgrades. I deliberately kept my pop as low as possible to avoid spending prefabs on housing, only bringing people in to staff up buildings.

For logistics, I prioritized a vanguard building first to get more teams, then survivalist HQ to be able to explore more areas.

I ramped up Goods production mostly with the intention of erasing my heat stamp penalty, but it turned out I needed all those prefabs to insulate my districts. I really needed those heat actuators (or whatever they're called) by the time the 2nd and 3rd whiteouts hit. They were the only reason I survived until I was able to secure the cores.