blowboat/grandpa
another obvious "don't do that", but I'll add another----Get a mirror and become comfortable using it competently.
Having a mirror and to be able to use while still riding straight and without wobbling is an extremely useful help.
The main use of a mirror is to follow what is coming up behind you, and if necessary, to pull over onto the shoulder. My mirror has a flat surface, so its much easier to judge distances and timing, whereas convex ones are notorious for not being good in this regard (been there, done that)
My mirror also is on my helmet, so its super easy to glance and get excellent info on whats incoming from behind, are they moving over a bit etc--but I realize that not everyone has the skillset to do all this at once and react with the right timing.
for me, these sort of situations are exactly why I use this type of mirror, it makes all the differnece in the world for safety.
please consider a mirror and becoming used to using it . Mine is a Take-a-Look mirror, mounted on my helmet visor. Also mounts on glasses arms.