Hee, I remember you! ("As much as you want!")

do successful authors ever dig up old books, edit them, and publish them once they're successful enough to get away with bending genres?

Yes. The example that pops into my head is Susan Kearney's book The Challenge--it was the first book she wrote, and something like her 20th to get published.

You don't have to sell the book of your heart to an e-press. Try submitting it. You might get lucky--you never ever ever know.