In late February, most areas with elevation in the Southern Appalachians are going to be fairly cold. We did a loop last year in early March and the lows were 20-25F. If that temp range is OK, there are many loops in the 35-45mi range.
A couple off the top of my head in NC -
Big Creek ranger station up to the AT and Mt Cammerer fire tower, stay at the Cosby Knob Shelter. Then, down the AT to the Balsam Mtn Trail and over to Laurel Gap Shelter on the BMT. Up to Mt Sterling fire tower and down the Baxter Creek Trail back to your car. Great views, two fire towers and big trees. 37miles
Pisgah Loop - Turkey Pen Gap along the S. Mills River and up to the Pink Beds, camping near the junction with the Mountains to Sea Trail. Up to the top of Mt Pisgah near the Pisgah Inn and stay the 2nd night near Sassafras Gap. 3rd day walk back to Turkey Pen Gap. Great mountain views, swinging bridge and river views. 34miles