Well, slavery having been abolished in Canada, no one, not even parliamentarians, can be compelled to be in government if they do not wish to be. If the government says, “This measure must pass”, whatever it is, and it does not, then it is in the power of the government to resign.
So I'm not sure that turning from a political convention, perhaps, which will morph over time, to a constitutional rule or a piece of legislation, or a House standing order defining a confidence vote as being a bill of national importance as deemed by the government, is particularly useful. It's a political issue, over time, and it is a fine calculation, as you know well.
If we create a crisis over issue X, and the opposition dares to take us down, do we think we'd do well in the politics...? That is a calculation that should remain in the realm of politics. That's why I said in my little opening comments that at the end of the day, the government can choose to resign any time it wants to. I'm not sure how much you can “pre-can” that and write rules about it that are going to be all that helpful in the future. I suggest that you go to the other end of the issue, which I would submit is in our tradition, and address a specific issue where you know there is an issue--namely, do you have responsible government or not, and can the House of Commons determine who is the executive or not? Write a rule about that, and then let convention and practice determine other issues.