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A light throttle whine sounds like it could be the differential whining caused by excessive backlash in the gears.
I had this in an Explorer I had. Coasting had absolutely no noise, light throttle had the whine, esp at higher speeds (50-70), and getting on it produced no noise (or at least couldn't hear it over the engine).
Put your 2nd and 3rd row seats down and see if you can be more precise in the location. Wheel bearing is also a possibility, but the throttle position makes me believe it is the differential.
Are you still under warranty?