Backing up a TT

We use cell phones for communication between driver and spotter. I'm the spotter, but as a veteran horse-trailer-backer I'm well aware that if I can't see the driver's face in the mirror, he can't see me. But sprinting back and forth from side to side as the trailer maneuvers into position, or having to put myself in mirror-friendly position where I couldn't see the back, or other side, of the trailer, finally convinced us to go to a better form of communication than hand signals. I've seen people using radios, too, but just being able to talk to the driver frees him up to look all around at whatever he needs to be watching.

For me, backing successfully into any space is directly proportional to the audience. I'll put that horse trailer on a dime if no one is around, but it takes 15 stabs at it if the whole barn is watching. :)