If you are intending to release the resource on the MP then you shouldn't think about doing this and instead should...
To then retrieve those settings when loading a forum, you'd need to hook into constructLoadQuery in \IPS\forums\Forum and do something like this:
protected static function constructLoadQuery( $id, $idField, $extraWhereClause ){
$parent = parent::constructLoadQuery($id, $idField, $extraWhereClause);
$parent->join('your_table', 'your_table.forumid=forums_forum.id');
return $parent;
}