No, you won't see separation, it will just create a bit more lift than it should and the drag reduction won't be optimized. It will still work well I'm sure, it could just be a little better if it were a tad higher. I figure you'd be 8" from the rear deck lid to the top of your Kamm.
Here's my overlay and Kamm shape attempts. Bigger detailed link below cause Ecomodder don't like big pics.
Big Copy of Template on Tempo