If by "boondocking" you mean dispersed camping, there is Sumter National Forest in South Carolina. It is in the Piedmont, not as warm in winter as the coastal plain, but likely warmer than Ontario.
Some of the campgrounds are open year round, some are seasonal with the open season outside your time window. I'm not sure about the season for roadside and dispersed camping.
Then there is Francis Marion National Forest on the Atlantic Coast, in an area where winter is more moderate. I don't know about dispersed camping, but there is at least one developed campground.
A problem with the National Forests here may be stay limits. I know that the campgrounds have stay limits, don't know how much of a move is needed to get around them.
AFAIK, there are no Long Term Visitor Areas on public lands in the Carolinas, the land use situation is different from the deserts along the California-Arizona border.
Tom Test
Itasca Spirit 29B