This snippet in a custom module will allow you to include domain names/ids in views in an ubercart orders view.

/* 
 * implementation of hook_views_data
 */

function MYMODULE_views_data() {
	
  //Assign the domain and uc_domain_orders to a 'Domain' group
	$data['uc_domain_orders']['table']['group'] = t('Domain');
  $data['domain']['table']['group'] = t('Domain');
 
  //Left join uc_domain_orders to uc_orders using order_id
  $data['uc_domain_orders']['table']['join']['uc_orders'] = array(
	  'left_field' => 'order_id',
	  'field' => 'order_id',
  );
  
  //Left join uc_domain_orders to uc_orders via uc_domain_orders, using domain_id
  $data['domain']['table']['join']['uc_orders'] = array(
  'left_field' => 'domain_id',
  'left_table' => 'uc_domain_orders',
  'field' => 'domain_id',
  );
   
  //Define a domain id field
	$data['uc_domain_orders']['domain_id'] = array(
	  'field' => array(
	    'title' => t('Store Domain Id'),
	    'help' => t('The domain id of the store from which the order was placed'),
	    'handler' => 'views_handler_field',
	  ),
	);
	
	//Define a domain name field
  $data['domain']['sitename'] = array(
	  'field' => array(
	    'title' => t('Store Domain Name'),
	    'help' => t('The site name of the store from which the order was placed'),
	    'handler' => 'views_handler_field',
	  ),
	);
  
  return $data;

}

Refresh the cache, and you're away!