SA locos generally ran with a clear stack or with haze. If you talked to the crew at a water stop and told them where you planned to be you could get great smoke. A few bottles of their favorite beverage was always a good way to seal the deal. The best time to visit SA was winter when you were guaranteed steam effect even if they weren't smoking.
I remember on the 611 ferry move back to Birmingham after the last Asheville trip, Dave Goodheart gave the crew two boxes of Krispy Kreme and the result was plenty of smoke at the Wells viaduct at Toccoa.
Michael Allen