Suggestion: Two additional security measures

Suggestion 1: Prevent ClickJacking with

function SG_Block_ClickJacking() { header( 'X-FRAME-OPTIONS: SAMEORIGIN' ); }
add_action( 'send_headers', 'SG_Block_ClickJacking', 10 );

Suggestion 2: Disable File Editing in WP Backend
insert additional item in wp-config.php
define( 'DISALLOW_FILE_EDIT', true );