I'm guessing Walter or some other local folks will chime in with good suggestions. I am reluctant to suggest anything because our climates are so different, and something that does well here may not be suited for Georgia. However, it sounds like a great question for a good nursery in your area. I always like to see and touch the plants I am talking about anyway, so I recommend getting some ideas there.

How about a weeping bottle brush tree?

Consider Emerald Green arborvitae...it's the right size

I think you could easily keep a Little Gem magnolia at 12 feet.