Create custom template for a specific node without node ID?
Sure, you can use hook_preprocess_node() or hook_preprocess_page() to suggest any template you want for a node or a page.  I am suggesting both because of the name you gave in your question page--node--11.tpl.php is really a page template not a node template.

Regardless, you could do this:

function YOURTHEME_OR_MODULE_preprocess_node(&amp;$variables) { 

  if ( /* whatever logic */ ) {

    $variables['theme_hook_suggestions'][] = 'node_whatever_you_want_to_call_it';

  }

}


or

function YOURTHEME_OR_MODULE_preprocess_page(&amp;$variables) { 

  if ( /* whatever logic */ ) {

    $variables['theme_hook_suggestions'][] = 'page_whatever_you_want_to_call_it';

  }

}


and now when that node is rendered, it will use node-whatever-you-want-to-call-it.tpl.php or if the page, page-whatever-you-want-to-call-it.tpl.php.