"For the shelter warmth, if it's not sealed 100% I don't see a problem burning a stove, candle or even fire inside."

Respectfully, I don't agree. There's a myth that CO is sufficiently heavier than air and will vent out of openings in the tent. In fact, carbon monoxide is slightly lighter than air and diffuses evenly throughout the structure. You're seriously at risk of dangerously increasing the CO to O2 ratio, even in what you think is a vented tent. PLEASE reconsider.