you can do walk-ins anywhere you can find access such that you are on public property. one advantage of paying for a boat ride is that the captain will tell you the basic "lay of the land" at the dive site. he will tell you where the gravel bed is (this is what you are searching for because this is where the fossils are), where there are drop-offs (if any), where the bottom is hard pan (can't hold on here due to the current), where the sand is (very few fossil finds here), where the log jams are (entanglement concern), and other features of the bottom.
if you are going to do walk-ins here, you need to learn what type topography the alligators like to make their nest in. they are territorial and it is best to stay away from their territories. alligators are seldom if ever found in the center/bottom of a river. the edges of a river are a different story.
boats: DANGER...boats kill divers in this neck of the woods. USE A DIVE FLAG! USE A DIVE FLAG! USE A DIVE FLAG!
You can use any public boat landing. BEWARE.... you need to use one that has very few boats coming and going. Intoxicated boaters will kill you. Its a fact, and it happens here.
Below is a link to photos of a local public walk-in. If and when you decide to go for it, I will provide directions. The far side definitely is alligator territory (stay away). This is a channel for a lot of boat traffic. USE a dive flag! Also use a compass or dive reel to find your way back. I dove here off a boat. The bottom is not unfriendly. Mostly brown sand with some gravel beds and sharks teeth. You will have to search for the gravel beds. USE a dive flag!
Walk-in