I take care of this in a different way. I use my BOB for camping a couple times a year to rotate my perishables. I also do NOT pack a tent, air mattress and some of the other "Camping" items that are found in many BOB's. My BOB is a get home bag and I have designed it as a 100 miles or less GHB. The area where I live will provide me with many opportunities to get out of the weather with abandoned buildings, out buildings and such. My tent is a simple survival tube tent, it and the emergency blanket along with my 50 degree bag will get me through a cold night, not comfortably, but alive. The Survival blanket I use as a cover for the bag so that I am not bathed in my own sweat at the end of the night. Doing it this way allows me to regulate the temperature and vent as needed. As for ground cover, I'll use old leaves and brush and whatever else I can find as insulation and bedding.
Now as for the camping end of it all, I keep my Therma-rest unrolled, valve open and hanging with my sleeping bag in the basement. The cells will break down over time, but as long as you have no punctures or a broken valve it will act as an air mattress and keep you off the ground. Down bags will loft better than a synthetic one as long as the tubes inside the bag remain undamaged. Hanging them makes them last longer, but it also settles the insulation if they are left hanging in one direction too long.
I personally would not use a down bag the way my BOB is set up, once my down is wet, it's as worthless as a, well, wet blanket. A synthetic bag will provide warmth even when wet. Newer bags pack nearly as light and small as a down. The only time down really gets the nod any more is if you are going to do extreme cold weather camping. I've use my synthetic bag with no tent in sub-temps and slept fine, albeit with snow covering me in the morning.
