There are plenty of 'sexually liberated' characters in Jane Austen's books. Willoughby, Henry Crawford and Mary Crawford, Wickham...
Wait, I'm beginning to notice a pattern, they're all villains. Austen knew degeneracy existed, she just didn't approve of it.
Are you unfamiliar with the cross-dressing that occurred in the Regency Period?
Gender attire-bending masquerades occured, and it was not unheard of for upper class/elite women or men to shift attire; it was tolerated as form of attire play and eccentricity.