It would probably be better to use a shortcode, then add the shortcode into a section at the bottom of the post.
For example:
add_shortcode( 'post_navigation', 'tu_post_navigation_shortcode' );
function tu_post_navigation_shortcode() {
ob_start();
if ( function_exists( 'generate_content_nav' ) ) {
generate_content_nav( 'nav-below' );
}
return ob_get_clean();
}
Then you can add [post_navigation] into a section.
That way the style of the page will remain consistent.