Perpetua "Pepper" is pretty cute. For any of the others, I think Pepper is too far a stretch.
Piper is fine as a name in its own right, imo. Modern and fashionable but perfectly respectable ... more so than Pepper, really.
I love
Parthenope and
Persephone in their own right, without those nns. Without any nns, probably. (Actually, I do like Seph for
Persephone.)