>>2225607>>2225615>>2225617god damn what it with LARP /in/cels giving useless advice about things they've never tried
>>2225604Boiling water in a nalgene, wrapped in a sock is standard practice in winter camping. It allows you to push your bag an extra 5-10 degrees, and ensures your water doesn't freeze in the morning.
If you want to upgrade your summer bag to autumn it's more important to get sufficient winter sleeping pad insulation