These caravan mirrors from Repusel from the Alufor series are perfect for the Tesla Model Y.
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. With 3-4 suction cups - one of them extra large - it is secured against slipping and tightened with 2 screws at the top.
The exterior mirror can still be folded even with the caravan mirror installed. The view can be flexibly adjusted as the mirror can be rotated in all axes.