Do you equip your "backup spotter" with a walkie-talkie?

We tried the walkie talkies but my wife would start talking as she pressed the talk button so I usually heard just the end of her comment. We have found the best solution is for her to stand at the driver's side back corner of where she wants the trailer. She will yell if I am going to stike something. I found this method reduces the friction between us. I am still trying to figure out why she occassionaly points up with the middle finger - I can't get the trailer to move that way!!