Lady Susan, unique among Austen's novels

Finishing Jane Austen's short novel, Lady Susan, did check out some facts on WikiPedia and found I was mostly right in my surmises yesterday: it was an early work, she did finish it, but it was never submitted for publication and was published finally about a century after JA died (in the late 19th century, that is). Wiki also wisely noted how different Lady Susan is from other Austen heroines and how this novel breaks w/ the convention of the novel of manners of Austen's day - she was way ahead of her time, in other words. Yes, Susan is smart, acerbic, manipulative, self-interested, and funny - perhaps a descendant of Beatrice (Much Ado). She's a cougar, as well - flirting shamelessly, even cruelly, with a man about 15 years younger than she - and a selfish mother and friend: indifferent to her daughter and trying to marry him off to an idiotic man of wealth, and carrying on an affair - Austen is very circumspect about this, but even so it's pretty advanced for her time - with a married man. This clearly was a path that would not have led to literary success, maybe not even to publication, and the works Austen published in her lifetime are all so different from Lady Susan. They are driven generally by a young woman pursuing a match - sometimes for herself, sometimes for a sibling or a friend - and the young woman is smart like Susan but honorable and above board; her character flaws such as they are a degree of naivete or lack of self-knowledge - Liz Bennet's prejudice, Emma's "clueless" inability to see who's in love with her, for example. They are often (not always) from a family of middling wealth and therefore in need of a good match - similar to Lady Susan in this case - but they are not, like she, mercenary. Of course all of Austen's novels are comic in form - leading to marriage and assimilation into society (Persuasion a possible exception) - but in Lady Susan the marriage at the end, hers at least, is obviously doomed and meant clearly to serve as the "beard" for her continued affair with Mainwaring (Whit Stillman in his film Love & Friendship is more direct and overt about this than Austen could have been) and the society to which she, and her daughter, are assimilated is rotten at the core.