what if I used two sleeping bags at once?

[bfayer]

I tried it in my tent in 20 degrees. Worked well actually. Quite warm and the weight was 2 pound 8 ounces total

These must be very light sleeping bags to average less than a pound and half each. My MB UL #5 weighs 1 pound 4 oz.

If it works for you, there's no reason you can't do it.

Sent from my Galaxy Nexus using Tapatalk

[johnnybgood]

I would suggest taking your lightest sleeping bag, long johns, down jacket and camping out in the yard on a few nights below freezing. I have a taken a 20 degree bag to - 5 by supplementing it w/ a fleece liner, fleece jacket, down jacket, long johns, hat, mittens, and wool socks.

I guess the biggest point is to try a lot of different combinations before you add the extra weight and bulk to your pack.

+1- Try fleece base layer with a down vest ,keeping arms unrestricted ,with wool cap and socks . If you wear what you bring then you may find that to be equal of stowing a second bag in your pack.
You've got time to test different setups before your start date.

[Zep]

I'm doing 2 sleeping bags, both fleece bags (50 d rating). Originally was just doing one, but I was cold under 20 (wearing my thermals +whatever necessary). Then started putting the fleece bag in my synthetic bag which was beyond warm, but too heavy. So now I'm doing 2 fleece which has tested great so far, but I'm going to keep testing.
Also sending one back when warms up, and swapping out when 1st one needs replacement.

[10-K]

The only thing about fleece is that it's heavy and doesn't pack small.

I personally like the 2 bag option with fewer clothes best.

If you're hiking, you won't need a lot of warm clothes. If you're willing to go from hiking directly to your bag then you'd save weight carrying 2 bags and fewer clothes (if the bags are top-tier down bags).

But, if you like to stop early and hang out or for whatever reason have a hard time going directly into your bag then you obviously need clothing - in which case you don't need 2 bags.

[Stir Fry]

The formula I have seen is [x -(70 - y)/2 = z] provides this:

X=45 and Y=55: 45-(70-55)/2=15