Thank you bcworks.
Looks like I did not understand the filters correctly..
Solution:
add_filter( 'vc_shortcode_set_template_vc_single_image', 'addVcSingleImageShortcodesTemplatesCustom_551124' );
function addVcSingleImageShortcodesTemplatesCustom_551124() {
$file = plugin_dir_path( __FILE__ ) . '/template_override/vc_single_image.php';
return $file;
}
Now the vc_single_image.php is in my plugin directory and cant be overwritten plus I can customize the content.
Thanks for the help.
