It's an interesting theory, but as someone that lives in KC, you know where each bridge that crosses the river is located. IMO I can't see how she would think she could end up anywhere but the river by going down the boat ramp.
I've driven her suspected route, and even if she was headed to 635 there were numerous places to turn around without driving down a desolate Park road and ending in the river. Also, I was just at this park yesterday, I still can't find the logic in turning anywhere near the boat ramp. It just doesn't add up to me. There we countless parking lots and turn arounds prior to the boat ramp and no matter which direction you're coming from, you'd have to really want to end up on that boat ramp IMO.
I personally think her car being on the boat ramp was either intentional by her, or someone that wanted to cause her harm.
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