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I'm not sure if I haven't already joined your Discord.  If I haven't I will do so.

I think it's possible to make female protagonists work and I've read several that I really enjoyed.  Those that stand out are:

Good Girl Gone Bad
Our Red String - both by Eva KIss
Glamour by Dark Silver
Luna's Fall From Grace by Frozen Synapse

Each of these have different features that make them interesting and some share features in common that make them interesting.  Both Luna's and Girl Gone Bad allow the player to determine how corrupted, or uncorrupted, the MC becomes.  That can be fun for both extremes, the ones that want to turn the MC into a complete slut or, by contrast, want to develop the romantic interest of the MC.  Our Red String has that same aspect but not to the extreme that Good Girl Gone Bad does.  Glamour also shares that feature but with the MC there, Kate, it's pretty much an imperative that she must be corrupted.  I think this corrupt-ability factor is essential to female pro's because, regardless whether the player is male of female, facing the fact that people that play these games are essentially those with extreme sexual natures, it permits the player to be personally engaged in the process and development pf the MCssexually.  I think the issue with Penny is that she is basically, too good.  She is altruistic and righteous in her nature.  It is tough to parallel that with an aggressive sexual nature and make it believable.  Her character, as it is, is good for a novel but not so good for an AVN.  Or... at least... challenging for an AVN.  

However, if it were me, rather than abandon the story I'd try to find the route to develop her character so that she becomes an advocate for open sexuality.... permitting all of the popular excepted expressions of it.  She is in a lesbian (or at least bisexual relationship) and I think adding a more lascivious nature to her character and seeing her expand her own 'harem' would ad depth and appeal to her as an MC.  And paths could be developed that permit Penny to take positions relevant to the player's sexual interests.