So, you're making a toy hauler, right? You might want to take some time and study plans plans for them to learn how others have worked it out.
The challenge with working in the cold, besides the discomfort, is getting glues and caulk to cure and paint to dry properly, as you're no doubt learning.
Keep us posted.
“Heaven goes by favor. If it went by merit, you would stay out and your dog would go in.”
― Mark Twain