Skippy: I don't see why you'd have a problem camping all winter in SC and NC with your current camper. Your water lines aren't going to freeze if you are heating the inside of the camper. Outside, your hose may freeze, but you can get a heated hose or just unhook and drain your unheated hose at night. Of course, no camper can prevent the campground's faucet from freezing, but that's fairly rare down here.
As for holding tanks, unless they are full, freezing shouldn't be a problem. You just won't be able to dump until they thaw out. Which usually doesn't take long down here.
We camp every single month, year-round here in NC, with never a problem related to cold weather. We've often camped in the snow and last Thanksgiving it dropped to 14 one night with no problems.
Of course, if you're wintering in Michigan or Wisconsin it's a different story. But where you are or even in the NC mountains, I don't see any reason for getting new camper unless you just want something new.
Yes, we end up winterizing and dewinterizing 4 or 5 times a year, but the 10-minute process is worth it to us. If the temp is going to be below freezing for days on end (fairly rare in NC and SC) we stay at home. Otherwise, we will be out there.
2013 Surveyor SP220
2010 Silverado LT 5.3 V8
The world is a great book, of which those who never stir from home
read only a page. - St. Augustine