Move Feature Image under the title

add_action('do_meta_boxes', 'customposttype_image_box');

function customposttype_image_box() {

	remove_meta_box( 'postimagediv', 'customposttype', 'side' );

	add_meta_box('postimagediv', __('Custom Image'), 'post_thumbnail_meta_box', 'customposttype', 'normal', 'high');

}