Think an extra ref will just result in a shot at goal for both teams from halfway in a 79th minute tbh - and I think it may be the fairest way.I'd turn the clock off until the ball's in for a start. Pretty sure that would cut back on the fannying around. Oh, and start to call crooked feeds too.
Similar to rucks though, reffing them isn't an exact science. There'll always be an element of interpretation except in the most obvious cases.There's maybe an argument to be made for another ref on the opposite side of the scrum or the TMO keeping a closer look out for a prop slipping his bind or refusing to take a square hit.
Perhaps we outlaw scrums for the last 10 mins so it's only tap n go, or a lineout restart in line with the knock on. Removes the crapshoot 50/50 chance and threats from whichever team were stiffed. Plus the wallabies scrum is ****, so it'll help us. Maybe.