Interesting to see that idea put into practice and Cheesie regarding your point, I was talking to a couple of mates recently who are teachers at AIC and GPS schools here in QLD and involved in the rugby programs. There has been discussions about rolling out player assigned jerseys from next year with these tackle height banners and you must only wear your jersey because the height line is correct for you.
It could be the way the sport goes, similar to basketball, NFL, soccer etc and moving away from the numbered positions. For example all props in the squad are issued a number between 1-10 and get a custom fit jersey with a bright tackle height line put on it.