In calling for the Convention, each state could in theory give its' delegates a mandate to address only one issue.
True.
However, by its nature a Constitution Convention is not limited to one issue. The opportunity for mischief and the pressure to do so would be enormous despite instructions from the states to their delegates. That is why I proposed a single issue Council of States.
A Council of States by design would have only one issue. If it was being ignored by an unresponsive federal government, with the stroke of a pen it would become a Constitutional Convention the federal government could not ignore under threat of dissolution.
Very treacherous waters we tread here!