Good luck on your hike. It's hard to say, but the Smokies in March can still get really cold. The 40 degree quilts will probably suffice, I say probably. You might want to have an extra layer or two, and I would definitely check the long range forecast before packing or heading out. If it might affect your logistics, remember that the road from Gatlinburg, TN to Cherokee, NC is closed due to a landslide--you can still get to Newfound Gap from the TN side.
"My goal is to live long enough to become a character."