I'm not familar with the specifics of the South Beach diet, but I am trying to do Atkins/controlled carb.
I like the diet V-8 SPLASH product. Forget the exact flavor, but IIRC, it is 3g carb per 8 oz serving. The flavor is more like a berry juice drink than tomato juice and it has quite a few vitamins in it. Might be worth trying to see if you like it and if it is OK for SB. I use it instead of orange juice in the morning.
Best wishes -