In normal times, I would say Standing Orders would suffice because Standing Orders are the rules of Parliament and should be respected as such. They aren't always. That's why I suggested that if something is done, it should be done through legislation.
To carry it through, my belief is if you use legislation, you should not tinker. The examples I gave of long sessions, short sessions, long prorogations, short prorogations, I think indicate that we can't cover all circumstances in legislation. We have to leave something to somebody's good judgment. That's why I say, one, legislation, and, two, a majority of the House to support a prorogation.
I'm not sure that's the right way to go, but I don't think Standing Orders are the right way to go.