Looks Nice. Why such a big gap. ( Make it big And cut it to fit) I would think you would want that tight and a cover in the front too keep stuff from getting in there with no way out or something getting lodged in there,now that you have two surfaces that close together. Maybe make one that covers front and overlaps to the back one,that way there would be no trimming just let it overlap an 1" or so on the back.
Just a thought.
Chuck