The fullback should join the line in attack and drop back in defence, not just sporadically. for a breakaway like this he needs to just go for the man with the ball in the 22 at least rather than just watch them score in the centre, at least force them out wide.
I also think there should also be at least a winger back in defence as you can kick past the fullback or you can just kick to the corners and isolate the fullback too easily or be isolated the same way.
Ideally I'd like a pendulum like the first picture where the 14 will drop and the 15 will move across behind the 11 like they're all connected by string if the 11 joins the defensive line. That way there's always 2 back but the SA way might be easier