How to stock a 55 gallon betta sorority?

So, I’m getting a sorority. Mulled over many other plans, but have ultimately settled on this one. I have kept betta splendens before in communities, kept several male and female betta alone through their lives. I think I’m qualified to try one.
Aqadvisor seems kind of bad for this, seeing as it really only calculates bioload. Inch-per-gallon also seems bad.
My current idea for stocking is getting about 17 female betta fish, 11 Rummynose tetras, 11 green neon tetras, two bristlenose plecos, and about 11 albino Cory catfish. Good stocking? Bad? More or less females?
They’ll be from cups at the store, as the closest store to me that keeps them together is unfortunately three hours away. If it’s absolutely imperative they’re siblings, I can look into a sorority pack.