Welcome.
I'm in Brunswick which is about 60 to 85 miles south of Savannah, but I spent my childhood up there which was good times!
I am not sure if I said this before, but it takes lots of practice and safety in order to avoid ending up like roadkill or even worse. In order to ensure you are able to get your first freight train out of Savannah, the very first thing to do is completely avoid the Southover yard (next to I-516) as it has a military base lined up right alongside the yard. I'll tell you something I already read about and learned about - and it is up to you to decide how and when to handle it:
The Norfolk Southern yard around Garden City/Port Wentworth - sends their IM's toward Austell (west of Atlanta) and their GM's to Macon to say the least.
The CSX intermodal facility with their north entrance facing Interstate 16 and south entrance next to US highway 17 sends their IM's directly from their facility to Chicago and Memphis. They also get additional IM traffic from the Tropicana units and UPS piggybacks that go between Jacksonville and New Jersey. The same yard also gets traffic from double-stacks that run between Jacksonville and Charlotte, NC.
Otherwise if you are in fear of being seen altogether, the easiest ride I ever did was a Norfolk Southern empty auto rack consist that goes between Vance, Alabama (southwest of Birmingham) and my current home of Brunswick. Each empty auto rack provides plenty of cover and walking space. I safely bailed after passing Jesup and never really went to Vance since I was teaching myself how to handle auto racks at the time. The Georgia Ports Authority does run both Savannah and Brunswick.
So in short, you can go to Macon and Atlanta on the NS line. And you also got an actual main line that goes between New Jersey, Baltimore, Washington DC, Richmond, Charlotte, Charleston, Savannah, and Waycross/Jacksonville on the CSX.
I still find it best to teach yourself how to safely get on and off of freight cars - definitely watch for suicide IM's because that is one curve ball that either company can throw at you.