I'm wrapping up making a bait tank for my kayak out of a 10 gallon Rubbermaid Brute trash container. Could easily be upped to a 20 gallon container for your john boat.
A buddy of mine who is totally brilliant has built a couple for me, and they're by far my favorite rods. One is a 7' spinning rod on a MHX blank with Ti Recoil guides, the other is a casting rod set up for pretty much any heavy action freshwater needs short of big swimbaits. That one is a St...
Jones Bridge Park on either the Fulton or Gwinnett county sides is good. Also check out Azalea Park/Bull Sluice Lake (small, shallow Hooch impoundment).
Otherwise it'll be office parks and neighborhood ponds.