I don't know if RF can handle the cold of winter days like a large sulcata can, I don't think so. That's why you would need bigger than just one box, so he would have enough room to live inside the box/shed all winter. Then in summer it could be used as it's night box. @ZEROPILOT can answer that better than I can. I can't say I have ever seen a RF go outside in the colder winter temps.So if I build a night box do you allow him access to outside even in winter?