Son 1 just sent me a link to this. It's a heated sleeping bag 
http://www.salewa.com/product/trekking-sleeping-bags/sigma-hot-flex-sb-alpindonna
Not sure tbh, I like heat at my back too. I generally take a hot water bottle if it's baltic out when I'm camping.
Not terribly bushcrafty, but a damned site easier than digging a trench fire and heating stones
cheers,
M

http://www.salewa.com/product/trekking-sleeping-bags/sigma-hot-flex-sb-alpindonna
Not sure tbh, I like heat at my back too. I generally take a hot water bottle if it's baltic out when I'm camping.
Not terribly bushcrafty, but a damned site easier than digging a trench fire and heating stones

cheers,
M