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Almost, but not quite, sprayed a mouthful of red wine on my 40" monitor, which makes the measurement much larger than 3.5", but I won't bother with a ruler because he said that wasn't the measurement he was looking for.
The measurement I have for the side area at the bottom of the door panel is 61" going from trim to trim. In your photo, you have the line a bit higher where the trim starts to curve so it would be slightly bigger.
Also going along the bottom edge of the door panel from back trim to the front edge of the door is about 59.25".