Alternate month/single-event.php

<?php
/**
 * Adapted version of month/single-event.php.
 *
 * Displays the post thumb in the grid *only* if it is the
 * only event showing that day.
 */

if ( !defined('ABSPATH') ) { die('-1'); }

global $post;
$day = tribe_events_get_current_month_day();
$event_id = "{$post->ID}-{$day['daynum']}";
$start = tribe_get_start_date( $post, FALSE, 'U' );
$end = tribe_get_end_date( $post, FALSE, 'U' );

?>

<div id="tribe-events-event-<?php echo $event_id ?>" class="<?php tribe_events_event_classes() ?>">
    <h3 class="tribe-events-month-event-title summary"><a href="<?php tribe_event_link( $post ); ?>" class="url"><?php the_title() ?></a></h3>

    <div id="tribe-events-tooltip-<?php echo $event_id; ?>" class="tribe-events-tooltip">
        <h4 class="summary"><?php the_title() ?></h4>
        <div class="tribe-events-event-body">

            <?php echo tribe_events_event_schedule_details() ?>

            <?php if (has_post_thumbnail() ) : ?>
                <div class="tribe-events-event-thumb"><?php echo the_post_thumbnail(array(90,90));?></div>
            <?php endif; ?>

            <p class="entry-summary description">
                <?php echo get_the_excerpt() ?>
            </p><!-- .entry-summary -->

        </div><!-- .tribe-events-event-body -->
        <span class="tribe-events-arrow"></span>
    </div><!-- .tribe-events-tooltip -->

</div><!-- #tribe-events-event-# -->

<?php if (has_post_thumbnail() && 1 === $day['total_events']) : ?>
    <div class="<?php tribe_events_event_classes() ?> lone-thumb-container">
        <div class="tribe-events-event-thumb"><?php echo the_post_thumbnail(array(90, 90)); ?></div>
    <div>
<?php endif; ?>