I have come to believe we all gave KC way too much credit in this murder. Many of us, including myself, believed she took the time to find a place to put Caylee where she would not be found. (like feeding her to the gators)
It appears this girl is just another run of the mill criminal who does stupid things which will put her away for life. I now believe she just dumped that bag as close as she did because GA was on her trail and she knew he was going to catch her if she didn't.
She tried to play "backwards" and give hints, but she was too stupid to even do that well enough that someone in the family could move the body.
I am convinced she dumped that baby on the 24th (if that is really the date GA got his gas cans) in a fit of panic and intended to go back and move it later, but the water took over the area and she could never find it again. It may be she got to tied up in her "life with Tony" that she never even bothered to go back.