Thanks for the input! I was able to get the noise reduced by using the raytracing quality switch a few days ago just as you said, so at least that is quite manageable now. I don’t think cube maps would work for me, as I am making a vr experience, and rearview mirrors should be as realistic as possible at all times. I have tried various things to get a good quality reflection, but I keep running into different troubles. I have another topic open on the ghosting with opaque materials, and weird see throughs on translucent materials with opacity at 1.
If you think you have an idea on how to create a nice clear reflection of a moving mirror please do try to post a video of your result, I would be most intrigued!