Change cluster image

I installed the custom plugin to allow modifications via the custom.js file.

I successfully changed the image for the individual marker icons via:

/*Add path to custom marker AT-03-01/-2018*/
GeoMashup.addAction( 'objectIcon', function( properties, object ) {
       // add path
               object.icon.image = properties.template_url_path + '/images/marker_orange.svg';
} );

My last step is to change the image(s) of the cluster icons. The original reference is in this plugin file: https://github.com/cyberhobo/wordpress-geo-mashup/blob/master/js/geo-mashup-markerclusterer.js

I am looking for similar “addAction” code to correctly create a path to my custom images, similarly to the individual marker icons above. I have been searching, reading, and attempting every potential solution I could find through this plugin’s archives as well as the web in general and have not been successful.

Any ideas are very much appreciated… thanks!