Site Install extra options checkboxes are difficult

Relating to the excellent features added in #1198956: Site Install: allow passing additional form parameters;

I have a site install option in my .profile file that has a checkbox with default set to true:

$form['checkbox_item'] = array(
    '#title' => st('Install custom config set'),
    '#type' => 'checkbox',
    '#default_value' => TRUE,
  );

In drush site-install, I would like to set it to false. However it is not as easy as: providing key value pairs such as :
drush site-install standard my_profile_form.checkbox_item=FALSE
or
drush site-install standard my_profile_form.checkbox_item=''

This is because of the quirks of 'checkbox' input type and its return of value - see the implementation of form_type_checkbox_value() and the comments within for more information.

I found a reasonable workaround to get going - by not passing the value to the key in the call:
drush site-install standard my_profile_form.checkbox_item
(although, it does throw a warning: "undefined offset: 1 site_install.drush.inc:126")

Trying to come up with a better solution is tricky as the roots of the problem lie elsewhere.