Whining noise coming the rear, near the rear wheel usually is from the gears in the final reduction case. However, this happens mostly on deceleration, especially from higher speeds. When the engine is loading the gears, the teeth are worn in with each other for load and don't produce much, if any sound, as you described. BUT when the rear wheel is reverse loading the gears (deceleration), it will normally produce a "whining" noise. This is normal. Have you checked the oil level in the final reduction gear case? Are you using GL 5 75w up to 140, synthetic, preferably. Might be a good idea to remove the CVT cover and inspect the belt and sheaves for wear. If all is good there, then take a look at the clutch. Good luck and keep us posted as to what you come up with.
Mac
