I couldn't give a rats about the politics of it. There are monarchists and republicans on both sides. The monarchists ran a dishonest campaign, and it had the desired effect.
Why not make the matter simple? A simple yes/no on the question of do you want a republic? Then, once that gets up, another ballot on the half-dozen models proposed. Simple majority has it.
What monarchist, who has the courage of his convictions, would disagree? Let me guess......someone like Little Johnny who wants to pretend he's the head of state when it suits him?