What I'm going to do now is disable Jetpack's OG functions and we'll handle it ourselves within the theme's functions.php.
For the moment, I've done this by editing the plug-in's files, but is there an easier way I can do this? A filter I can add to the theme's functions.php, perhaps?
You can use the following filter:
add_filter( 'jetpack_enable_open_graph', '__return_false', 99 );