How about a nice big sign "SMILE I AM CATCHING YOU ON MY REAR VIEW DASH CAM"
Ken
I installed front and rear cams a few years ago and did consider putting such a sign in, but then thought it might antagonise them. My cam caught a lorry driver on the M62 in a congested 50 zone round Manchester, bully other drivers out of his way to make progress. When he got to me, him in L2 (towing in L1) he yanked the wheel over deliberately to force me to let him in, so he could undertake. I was very lucky and was able to brake to avoid him, forewarned watching his progress in my mirrors. I recorded (audio) the reg number, where and the name of the company on my cam, at the time - then made a formal complaint to Manchester police along with the captured video and audio, which they made use of with my statement.