Should Umpires Use A Marker When Setting A Mark?

Last couple of seasons especially player's have been encroaching more and more when manning the mark, umpires usually notice it when a player is lining up at goal but anywhere else on the field I'm starting to see players creep over the mark by a couple of metre's in some cases but has seemed to go under most people's radar.
After watching the World Cup in Brazil earlier in the year and also they are using it in the A-League now was wondering if maybe umpire's should start using the spray soccer ref's where using in those competition's I mentioned. It's seems to be a simple spray that can be used to make a line that only last's a minute or so then evaporate's or whatever, guess the problem is that AFL game moves so quickly it would only be practical when a player is having a set shot at goal.
Maybe umpires should be just more vigilante!