After living with the dash rattle for over a year, I finally resolved it. Turns out it wasn't in the dash after all, but in the wheel well aft of the front wheel. If you turn the wheel to one side and pull the 3 bolts just behind the tire you can reach behind the cover and find a styrofoam piece covering the door hinge, that's the culprit. It vibrates when enough air gets behind the cover and hits the styrofoam. It goes all the way up to the dash which is why it sounds like it's coming from the dash itself. Mine wasn't sitting in there correctly (shifted to one side) so I put it in correctly and made sure the cover was also installed correctly to minimize any airflow to it. No more rattling noise! Hope this helps everyone. Pictures attached for reference.