Re safety.
I would urge you and your adult son to ride as much together on real roads, and even do some weekend test tours, to become more competent and comfortable with traffic.
** I highly highly recommend the use of a good mirror. I've been touring for about 30 years and I commute in a large city, and THE smartest thing I did about 25 years ago was to start using an effective mirror.
The heads up of a few seconds from a glance in a mirror for those occasions sketchy situations is worth all the money in the world.
but you have to use common sense and be situationally aware at all times.
And yes, at times its totally worth just pulling off the road for 5 or 10 seconds, and its a win win for everyone if very narrow and incoming trucks front and back.
I'm very happy with my helmet visor or glasses arm mounted Take a Look model that I've used for 10 years, much better than my handlebar mounted ones from the past.