Pro 3.1 - Change line feature legend patch to polygon type patch (or vice versa)

[KeithAddison1]

I have a legend that displays a mix of line & polygon feature.  The line feature are symbolized with a line, the polygon ones with a hollow rectangle.  I want them all to have the same patch, either all a singular non-closed line, or a hollow rectangle.  Doesn't matter which, as long as they're uniform.  Is there a way I can do this?  I am aware of the various patch symbol options, however there is no overlap between what the line patch symbols and the polygon patch symbols look like.  Workaround would be to make the polygon features into line ones first, but that'd take a good sight longer and make parallel dataset clutter.

[AubriKinghorn]

There isn't an easy way to turn lines into polygons, but you could add a duplicate polygon feature, turn it off in the map, and let it be in the legend with the line symbol name. Or only include the polygon feature in the legend if it has the same labels as the line feature. To remove a feature from the legend, expand the legend in the Contents Pane and uncheck the layer you don't in the legend. 

Would either of those work for your case?