For those who may still be looking at this, this is very easy to accomplish.
NOTICE: I am not recommending this as standard practice
I edited the plugin (since I’m only going to use it one time) and added my own Custom Post Types to the code.
define( 'BBCONV_TYPES', serialize( array( 'post', 'page' , 'cpt1', 'cpt2','cpt3') ) );
And done! It now searches my custom post types.
Secondly, I had 150+ posts, and there weren’t any options to adjust the number of posts per page, so I edited that as well.
$per_page = $this->get_items_per_page( 'posts_per_page', 200 );
Now I get all my CPTs that I want, and a maximum of 200 per page.
Again, under normal circumstances, I would not ever recommend editing a plugin. But for this one particular use case, it made sense to do it.