Lining a NF Blue Kazoo sleeping bag w/ a Marmot Atom bag.. a good idea?

[jacob_springsteen]

Planning a hike on the Georgia section of the AT for March 2015. I have an older NorthFace down Blue Kazoo. It has worked for most cold weather hikes alright but pack compression and such has reduced its loft IMHO. I have the lightweight Marmot Atom sleeping bag which is a late spring/ summer bag. I am thinking of using the Atom as an internal bag to line the Blue Kazoo and boost the insulation. The bags fit fine in this arrangement and I have enough sleeping space. Other than the carrying weight and backpack volume taken up by packing two bags, what other cons could there be? I am thinking I could use the Atom as a quilt over the Kazoo if the air is not as cold some nights. I don't want to spend the money right now to get a Marmot Lithium type bag. I envision the temperatures could hit single digits next March based on trail journal reviews of March 2014 hiker experiences.

[johnnybgood]

Like you already mentioned...quite heavy and bulky. While it might work fine there are other options out there .

Sea to Summit makes an excellent compact sleeping bag liners under a 1lb, with added warmth can increase the insulating ability of your bag.