1. Do you need a fire for warmth, as opposed to many bodies in a well-insulated (thick) debris shelter?

2. If warmth from fire is critical to survival, I suggest you learn to make very small, relatively smokeless fires, develop a set of safe practices for one or more very small fires inside your shelter, and pull the door shut. Consider a small line of fire in a trench, etc. Focus a lot on insulating your self from the ground. Be sure you set some stones to capture and re-radiate heat, even after a fire goes out.

Large fires around debris shelters may be a recipe for disaster no matter how vigilant you are.