Can I include get_posts in this array?

I’m assuming there is an option in the array that is meant to receive an array of options for the checkboxes…?

In which case, you can use get_posts to obtain an array of post objects (of which ever type), and then loop through this, to create an array of post titles:

For example..

$args=array('numberposts'=>-1,'post_type' => 'location');
$post_objs = get_posts($args);
$options=array();

foreach($post_objs as $post_obj):
     $options[]=$post_obj->post_title;
endforeach;

You then have an array of location names, $options which you can feed into your metabox array.

Disclaimer: I’ve not tested this code.