Story advice site

I write fiction, and it falls into two categories. Some is "publishable", and some isn't. The "isn't" is more or less pornographic, and while I don't mind sharing it, under no circumstances do I want it associated with my name.

In that second category, I actually have a genre venue with other interested writers, and we occasionally trade unfinished stories. I'd like some of their opinions on stories that are publishable - but I want to retain anonymity, and I want to avoid any publication on an indexed site.

The solution: an anonymized story posting site with attached forum, invitation-only. I post, and I give people specific individual keys to access the story and engage me in conversation about it. I can reveal comments between threads - but only at my discretion.

That seems pretty dang niche. I don't know if there's anything like a market.