Counterintuitively, the best way to make satellites less visible for ground observers is actually to make them MORE reflective. You want the reflection off the nadir side of the vehicle to be as specular (mirror-like) as possible so that the light reflected from the sun only makes it to a single point on the Earth's surface.

You can see that SpaceX (and probably other LEO operators as well) are already doing this: https://www.youtube.com/watch?v=rfJWli7YKPw

This video is a good visual illustration of that effect: https://www.youtube.com/watch?v=w8I25H3bnNw