I had a kumquat bush at Tallahassee, which is just below the Georgia line. It got killed back one winter but came back quickly. I suspect that kumquats are especially nutritious because you eat the flesh, peeling, and seeds.
The plant is fairly compact and I believe you could grow it in a movable container that you could be able to move indoors in the winter. Another option would be to plant it near the south side of your house and box it in with clear plastic sheeting. You could provide heat with a light bulb.
They are much hardier than citrus plants such as oranges. The 'Nagami' kumquat requires a hot summer, ranging from 25 ºC to 38º C, but can withstand frost down to about −10 °C without injury. It grows in the tea regions of China where the climate is too cold for other citrus fruits, even the Mikan (also known as the Satsuma) orange. The trees differ also from other Citrus species in that they enter into a period of winter dormancy so profound that they will remain through several weeks of subsequent warm weather without putting out new shoots or blossoms. Despite their ability to survive low temperatures, as in the vicinity of San Francisco, California, the kumquat trees grow better and produce larger and sweeter fruits in warmer regions.