I'm still interested in a better answer since this solution tinkers with the core installation, but I added the below file to get what I needed, with the following examples:
index.php?option=com_finder&view=search&format=json&q=%22my+searched+phrase%22 index.php?option=com_finder&view=search&format=json&q=my+keywords+to+find index.php?option=com_finder&view=search&format=json&q=my+keywords+to+find&limit=10
components\com_finder\views\search\view.json.php
<?php defined('_JEXEC') or die; /** * Search json view class for the Finder package. */ class FinderViewSearch extends JViewLegacy { public function display($tpl = null) { // Get the application $app = JFactory::getApplication(); JHtml::addIncludePath(JPATH_COMPONENT . '/helpers/html'); // Get view data. $state = $this->get('State'); $query = $this->get('Query'); $results = $this->get('Results'); // Push out the query data. if (empty($results)) $results = array(); $data['results'] = $results; $data['explained_html'] = JHtml::_('query.explained', $query); $data['explained'] = strip_tags($data['explained_html']); $data['params'] = $state->get('params'); $data['query'] = $this->get('Query'); header('Content-Type: application/json'); $response = new JResponseJson($data, 'Search returned '.count($results).' results' ,false); echo $response; $app->close(); } }