Views pager & exposed optional checkboxes

I figured it out... the place to do this is in hook_views_pre_render. FWIW below is what I ended up with for the three Exterior checkboxes. If no checkboxes are checked the second dpm shows that the Exterior array is gone completely.

function hook_views_pre_render(&$view){

 //dpm($view->query->pager->view->exposed_raw_input);
  if($view->query->pager->view->exposed_raw_input['Exterior'][1] != 1 &&
      $view->query->pager->view->exposed_raw_input['Exterior'][2] != 2 &&
      $view->query->pager->view->exposed_raw_input['Exterior'][3] != 3 ){
    unset($view->query->pager->view->exposed_raw_input['Exterior']);
   //dpm($view->query->pager->view->exposed_raw_input);
  }
 }