In relation to forward passes resulting in tries and offside-at-the kick rulings, I can't see why the NRL can't invest in "virtual marking" of the field?
The NFL highlight their 10 yard "down" line and swimming has a virtual world record line in front of the swimmers during the last lap. All of these would be calibrated on the venue being used.
Danger is that the NRL would be tempted to use it during normal play, giving more delays.
Could be brought in just for plays that end up in a try. They already check 20 views so why not 21??