I ordered a “puffy” camping blanket to go over my sleeping bag. My reasoning is that I would be able to “adjust” the amount of warmth that I needed during the night. I will update with my experience.
Hot Water Bottle Thoughts
As I said earlier, I had an actual rubber Hot Water Bottle with me with the intention of heating water on the camp stove before going to bed. Bed time was around sunset as most here can relate to and the temps were in the mid 40's. A hot water bottle at that time would have made sleeping probably too warm. So, I decided that I'd forego the idea until later if I needed it. Later when I needed it, it was around midnight and I did not have the motivation at the time to get up and heat water … lol.
My other thoughts on this approach were that the water would have cooled down in a couple of hours anyway and I'd be right back where I started. The cooled water may also even act as a “heat sink” draining heat away from me as one side of the bottle would be touching/compressing the underside of the bag with very little insulation because of the compression.
I'd liked to hear others experiences on this approach. Maybe I'm missing something. Maybe the heat from the water stays around longer than I think.
Booties are my next option to try.