SOP for Beckey and his contemporaries was just to lie down in the grass in their clothes and go to sleep. Of course, I'm sure that was in the summer and dry weather.
I had friends that were on a logging crew and when they were out overnight they would just use the burrito roll technique, which involves lying on a plastic tarp and rolling up in it to stay dry.
Really though, for the best warmth to weight ratio a lightweight sleeping bag and an added bivy sack in cold or wet conditions is your best bet. For the wieght of insulated Carhart overalls you could bring a -20 synthetic bag.