Cell phone with a Bluetooth headset is probably the best device for helping talk someone through backing. Hands free.
We've got a old RD822 Mack with a 12 speed. It's got 6 reverse speeds. You can start out in 1st and just run through them like going forward. 3rd is actually a good speed and comparable to other trans reverse low. In a way, I don't like that most stick shift automobiles have gone away. Not too long ago, everybody knew from a early age at least how to drive a stick pickup. I couldn't imagine a big truck being the first stick somebody has ever driven. I feel sorry for the trans and clutch in the training truck.