I think the current implementation is way too simple. Though I'm happy to be proved wrong.
I had to add new fields to the Listing Fields panel, and modify:
- root/templates/ja_findus/etc/extrafields/listing.xml,
- root/templates/ja_findus/html/com_content/article/listing-?.php,
- root/templates/ja_findus/html/mod_articles_category/list-locations.php,
- root/language/{your-language}/{your-language}_ja_findus.ini
- root/templates/ja_findus/helper.php
in order to implement as I wanted it.
The whole logic around determining open/closed was rewritten, and I included the use of JEvents to add public holiday overrides.
See screenshots attached.