Not exactly what you are looking for but we use "Thickness@Sheet-Metal"STK in the part custom properties to display the stock thickness in our sheet metal template.
Does that Property that you added automatically place the gauge dimension in the Property or do you still have to manually add the dimension from the part to the custom property value?
Scott, "Thickness@Sheet-Metal" automatically puts in the gauge dimension, so it updates when changing the sheet metal thickness. We had an edict from on high requiring the gauge or thickness to be shown in the title block, rather than a drawing dimension. Not a fan of this but the new property automates insertion in the drawing.