Currently on my 7th rewatch.

I double down. She's just devilishly hot. 
That's enough for me to believe she's our mighty RJ.

Rosalind Harker was lesbian after all. She wholeheartedly LOVED Summer.
Whenever someone who knows RJ refers to her as "he or him", they're simply misguiding PJ/audience.

Luckily for Cho, he somehow by his mother's prayers avoided waking everyday up to RJ's face, presumably doing blowJohns to his tiny asian red john.