You can always self-publish and announce to your fellow writers and readers on Medium. It’s strange you mention this ‘alternative history’ as I somehow stumble across the book written in 1855 on CPAR (Colored People of the Revolution). Excellent and eye opening introductions by Stowe and the author. I had no idea this book—or this rich history—existed. I started imagining the blacks being empowered by the revolution and where that could have gone.
Best of luck on your endeavors, sounds great.