Mirrors can be used to address this problem.
My past experience with mirrors was not among the best. The first mirror I tried long time ago was mounted on a long rode, so sensitive to vibration that only worked on a perfect tarmac. Even there, it's viewing angle did not make it actually usable. Finally, most of the rear view was obscured by myself.
As the community still recommended the mirrors positively, I tried again now and this time it was a success. The mirror I tested this morning has some optics providing much wider view than a flat mirror would, and it is attached to the end of the handlebar, far enough to provide the clear view. I needed to punch a hole at the end of the handlebar to install it, but looks that it is worthwhile.
I am also training to turn around for backward viewing.