Ultimately, I'm skeptical of the value of prorogation. I think there are certain circumstances in which it is useful to reset the parliamentary agenda and start a new session, but they are rare, so maybe the compromise would be to have set sessions so there is no issue of manipulation of timing and agendas and so on.
My initial preference would be to say that in a four-year Parliament there shall be two sessions, providing another session to deal with some emergency or other. In my view, that could and should be able to be put into the Parliament of Canada Act so that it's a legislated stipulation that there will be two sessions.
One could just simply leave it at that. It would work out to roughly a two-year period, probably, or one could say that the second September following an election, there shall be a new session. There are fewer constitutional questions if you just say there will be two sessions of Parliament, normally, because then you haven't really disturbed the Governor General's power of when to call it. If you try to nail down the date, then some people would argue you're actually taking the discretion away from the Governor General.
I believe that Parliament has the right and power to do that anyway, through ordinary legislation that would fulfill the requirements under section 44, unilateral amendments to the Constitution if need be. To recap, my short answer is to simply state there will be normally two sessions of Parliament and put it in the statute. One could leave a little wiggle room for the government or one could stipulate that it would be in the second September.