Hi, a little stumpie will def work as will a mullet. Most of your leerie's in the Swartkops river are in the 1 - 3 kg's region. As a result, I prefer to target the fish on artificials (poppers and leadheads).
The train bridge area is covered with rocks and red bait and is generally a difficult area to fish for leerie on live bait. The structure does result in some good kob being in the area though.
I would focus on the entrances to all the spruits from the rod club to amsterdamhoek. The fish tend to feed on a dropping tide as the water (and bait fish) wash out!