I use back button on my D5200 but it has caused me to change other things to avoid a few hassles. For example I had to disable instant playback of shots as the AE-L AF-L button doubles as the write protection while playing back images.
Aha, I was not seeing ghosts then.
Noticed that the D5200 wasn't able to AF as long as a picture is being (p)reviewed on the screen.