If you’re creating pages and field groups using code I would suggest that when you create the page in question that you store the post_id of the new page in an option value. Then alter the field group php to use that value for the location rule.
'location' => array (
array (
array (
'param' => 'page',
'operator' => '==',
'value' => get_option('my_option_name'),
),
),
),
