How can I make a heated night box?I would say yes. But to get her to eat it, I would chop it over the food, and over time, start adding more hay.
The new enclosure looks great! I’m not entirely sure how you would put a lid in it, though. Perhaps you could make something like a tent over it? Make a frame and drape tarps,heavy duty shower curtains, or something similar over it?
You could also just put in a heated night box, and make it humid inside. That way, you can lock her inside to sleep, and she can benefit from the humidity.
Everything looks great!