I would honestly be content with the vehicle if the rattles would just go away. It just makes the car so damn undriveable .
Get the service manual PDF from ebay. It shows how the entire dash comes apart so you don't have to guess and risk breaking something.
Remove everything you can until the rattles go away.
Line the mating surfaces of panels with foam weather stripping and wrap wires with foam or cloth tape. Reinstall a single piece, test drive, repeat.