Seems like the conventional wisdom is to hike in fleece (or synthetic), camp in down.

Packing for winter (in the southeastern US) strikes me as challenging, mostly for bulk reasons, and a winter coat for camp (or stopping) seems to be the biggest challenge. I have a down puffy (12 oz) but it's not adequate for a stop/camp item in winter. My only true winter coat is synthetic (Thinsulate lite loft). In any case, what (jacket-wise) is recommended practice for winter backpacking in this region?

Should one hike in a synth winter coat and just go slow enough to not sweat? [might be hard to go that slow, hauling a pack up 10-15% grades].
Find a way to strap it to the outside, if there's no room inside?
Hike in fleece and buy a warmer down jacket to stuff inside the bag, and skip the winter coat?
Drape your sleeping bag over yourself in camp until it's time for bed?

Not trying to go UL and would consider a larger pack, but mine is already pretty big and I have a feeling it's not the pack, it's my strategy.