I've investigated the little marina that is east of the presidential library. I found no mud, but did determine that it's not a nice or friendly neighborhood, and there is no handy private way to the water. The lock-and-dam system does wonders for shipping and real estate along the river, but it also does just as much to get rid of the really fun muddy sites.
There was a time when I would go down to the Red river, just about 30 minutes this side of Texarkana. I think I used to take the Fulton exit and go play under the bridge. Then they put locks and dams on that river as well, and people started settling right up to the river banks, as flooding was so much less likely.
If you do go there, I do have this word of GOOD advice. Be careful you do not put any removed clothing on a fire ant nest. I did that exactly one time. (proving it was possible for me to learn, at least as recent as 20 years ago)
I've heard stories about deep mud on some of the rice farms down in the SE, along the Mississippi river, but I don't know any of the farmers personally, to be able to ask to play in their mud. I had an acquaintance at one point who told me of having lost a pickup in a field that was far to wet to try and drive across. He said his buddy went for a tractor while he sat on a levee and drank his beer, and the truck actually sank so that only cabin was in view by the time the tractor arrived, and the insurance company totaled it without paying to remove it from the field. He said it continued to sink, and they have actually cultivated the field since, over the top of it. (Then again, stories here *can* get just as big as those in TX sometimes)
