How to add template to referenced node

I know how to add a template to a node in the template.php file.

function mysite_theme() {
  return array(
    'survey_node_form' => array(
      'render element' => 'form',
      'path' => drupal_get_path('theme', 'mysite') . '/templates',
      'template' => 'survey-node-form'
    ),
  );
}

But when I reference this content type using Inline Entity Fields the theme does not apply.

I have also seen how to change an inline entity from within a module, but can't figure out how to use it to change the theme.

function mymodule_inline_entity_form_entity_form_alter(&$entity_form, &$form_state) {
  if ($entity_form['#entity_type'] == 'node') {
    $entity_form['field_my field_ref']['#theme'] = 'referencedentity-node-form';
  }
}

This works when, instead of theme, I use an attribute like #markup to add some text, but I am trying to apply a theme. I have tried #template also, with no luck. Thanks.