GeorgiaBeeKeeper; I would not worry about winter, it looks like you have everything in hand. Actually, winter in the south is not much of a problem. It all comes down to having varroa under control with low numbers in August shown by alcohol washes, no disease, a queen with only one spring/summer laying season, and sufficient food for your area. Controlling the varroa mite is critical. Having hives in full sun is nice.
My winters here in northern Arkansas are not that different from yours and I have overwintered in only one deep box, but that must be packed with food stores at the end of October. I tell everyone that even though a colony can overwinter in a deep, I sleep better at night if I have a packed deep plus a medium. The end of October I feed until the stop taking it.
I would forget the quilt boxes, all the top insulation you would need is one inch of common foam board over the inner cover, and most colonies overwinter well without it. All my colonies have it winter and summer. Although some may disagree with me, I have found that upper ventilation is not needed in the South. Ventilation should come from the bottom of the colony through the entrance or an open mesh bottom board.
Trapping varroa with drone brood works well to reduce varroa reproduction rates, especially in conjunction with a brood break, but powdered sugar dusting will only remove 10 to 20% of the mites on the adult bees. When the humidity builds in summer the rate removed by dusting is usually only 10%. I don't know if the mites removed is worth the disruption caused.
I have been keeping bees for a while and I have found that if you do your work properly in the fall, you need do nothing until spring. Get the colonies properly prepared by the end of October, put them to bed, and then forget them until spring. Forget the sugar bricks on top, or the winter checks, or the thumping on the sides to see if they are alive, just leave them alone. At most, a walk by entrance check on a day warm enough for them to fly is all that should be done. And all that does is soothes your mind.
My usual overwinter loss rate is from 0 up to 8 % using these tips, and there is no reason yours should not be the same.