I figured out a way to use ‘visible’ as the property name. Just nest a container with the actual content of your component inside an extra blank Form, which you will use purely to set custom component properties. (You can set the space_above and space_below attributes of the outer Form to ‘none’ so that it doesn’t affect the layout at all.) Leave the visible attribute of the outer Form itself as True. Instead, have the custom component visible property toggle the corresponding attribute of the inner container nested inside the Form.
Here’s an example in which the “inner container” is a DataGrid (but it could just as easily be a column panel or a Custom HTML panel): Display a list of lists in a grid