Molly, you need to do the hot potato trick. Take a Nalgene and a small camp stove, boil a quart of water, and throw it in your bag at night. No more cold feet, guaranteed. I do this when I camp in the winter. Wrap it in a shirt or something at first though as it will be hot (duh, boiling!). The soft plastic Nalgenes will warp a little as they cool down, but its better than the hard sided ones, which can crack over time if you do it enough. Or you can just vent it half way through the night.
'01 Taco, DD, 33's, dented armor, squeaks, rattles
'80 Pickup, 35's, locked, armored, geared, lifted, and does ok when the hubs are locked in.