It's looks like you have hit/found everything up there. White Rock and Caney are just a little south of there. Back in the day, during the summer when the river got clear we could catch a few at the mouth of every cut that opened up on the river. Sometimes the smaller the cut was the better.
The river is gorgeous and fun to fish. Last month it was really good fishing, mainly the creek openings to the river like you said and the docks at Carolina. Recently it's been so-so. Yesterday was nothing, time before that I caught maybe 10 fish.
I was thinking of concentrating efforts on the mouths and deeper spots since it's getting hot and the shallow bite seems to be turning off.