Workaround to dynamically match Y-axis on two visuals?

Hi - I need to match the y-axis scale between a Waterfall and Stacked Column chart dynamically (can't hard code them as the range changes significantly depending on the filters applied).  I can add a dummy column or category to the column chart to make it match but then can't see a way to hide it, or set only its column width to zero.  Any ideas?