I don't like to spend too much time looking in my rearview mirror instead of looking ahead, so here's what I do:
- If I'm concerned about safety, I pull over at the first, safe opportunity to let the driver around me. I don't have the authority of law enforcement, so I cannot educate anyone. All I can do is create a safe space where/when possible.
- If I can't pull over, I put on my flashing emergency lights. This works in all cases. I've never had it fail.
Hand signals can be misunderstood. Same goes for horns. I tap my horn to alert someone if they can go ahead of me (simple communication), if they are getting too close to me and I can't move (informative alert), and (rarely) lay on my horn to communicate a serious danger. That doesn't mean I don't get angry, but drivers have rudimentary tools to communicate and the law dictates how we can respond, so I have to manage my emotions on the road.
I will say, pulling over or choosing to back off and calm down, provides near-immediate relief from stress. I've never regretted making the safer choice. I drive, for the most part, happy and chilled out because of it.
I've lived in 6 states, one territory, done two cross-country trips, and driven a 36-state loop. I've seen all manner of behavior and weather conditions and terrains, and it's best to just be happy, hang back, watch the traffic patterns, help when you can, don't get too riled, and kindly use those emergency flashers to communicate to those behind you to pay attention or watch out. We have to share the road - people have varying degrees of maturity and problem-solving skills. We don't just carry our cargo (kids, groceries, work stuff), we are also carrying the stresses of the day. So it's basically a crapshoot. You just do the best you can. Be safe. Make it home to the family who loves you. We have to look out for each other.