You want this because your client is confused, and setting a page to the homepage will not do.
But your solution is a can of worms waiting to explode in your face, so instead I have a much better solution!
Use the home.php template
In WordPress by default home.php is used as the homepage. If it is not found, front-page.php is used, and if that isn't found it uses index.php
So create home.php, put your homepage code in there, and then add a settings page with WYSIWYG editors and image uploaders for the various pieces of content. You can even link directly to the settings page from the frontend if logged in to the site.
If your client is still confused, use screensteps to show them how. Chances are your client is only confused because they haven't invested any time to read instructions or figure it out.
The added bonus of this is it doesn't leave any confusing steps like clicking on the listings and finding a single post available, and an 'add new home page' button that does nothing but generate warnings and permission denied messages.