Nice job! Do you think I could get away with a 3'x6' for Opo this winter. There will probably be only a handful of times he would have to stay in for 3 days at a time.
Remember, this is just a night box for sleeping and staying warm. Not an enclosure. Once I cut the entranceway, you will see. Sully will have room to wander in and out of her new “sleeping quarters”.
But on to your question. For a “few” cold nights n days, sure. But not the only space. But, 3 x 6 better than sub-par temperatures and catching a cold.