When we had our pop-up, we did many winter camps (in the Northern States, Indiana and Illinois) and had a fantastic time. Our pop-up did have a furnace, no bathroom. So we had to cart in our own water anyway, and used pit toilets anyway too. We had some great times. Funny, I know it was cold, but I don't remember the cold. The inside of the pup was always nice and warm and comfy. Kids were about 9 - 10 years old then, somehow they always kept themselves busy.
I discovered the advantage of electric blankets .... AFTER we sold our pop-up and went to a regular TT. DUH! If only we would have though of that when we had the pup! Life would have been REALLY sweet as we always had electricity.