The Custom of the Country - an early tryout or a faded reprise?

Really don't know how The Custom of the Country fits in chronologically with the Edith Wharton cannon, but I suspect it's an early work, a warmup for House of Mirth and Age of Innocence - touches on many of the same themes, the finely demarcated strata of the upper social classes in NYC in the early 20th century, a woman's struggle to make sense of the differentiations and to marry well and rise in class, contempt for work of any sort or at least indifference to it - the working men of this class, by which I mean attorneys and bond traders - seem to do hardly anything, and those who do work hard are ethnically marginalized (i.e., the Jewish character in Mirth), the Jamesian scorn for made wealth rather than inherited if made out in the provinces, and especially the struggles of a woman to gain status or at least security when she knows that she must rely solely on her wit or beauty. All that - but the main character, Undine Spragg, seems to me a wan sketch compared with Lily Bart or the cousins in Innocence - she's much more naive, even gullible, and definitely more shallow to the point of parody - like the pale, dominated sister in Middlemarch or Sense and Sensibility - books in which we identify with the intelligent if beleaguered protagonist and smile condescendingly at the limitations and foibles of the weak sister - but here there's no foil, or rather no lead character to make Undine a foil - and she's too much of a cipher for us to care much about. Still, the novel has all of Wharton's sharp observations (nobody has better incorporated decor into fiction) and her very witty phrasings - here again an echo of Eliot (G.) and Austen at their best - but it seems that this work is more like a tryout (or, if it falls later in her career, an attempt at a reprise): just compare the rather limited opera scene in Custom with the great opening Opera scene of Innocence.