These caravan mirrors from Repusel from the Alufor series are perfect for the Tesla Model 3.
They are easy to attach and remove and do not damage the mirror. The bracket is adjustable in length and is placed around the mirror. It is secured against slipping with 3 suction cups and tightened at the top with 2 screws.
The exterior mirror can still be folded in with the caravan mirror installed. The view can be flexibly adjusted as the mirror can be rotated in all axes.