I disagree that tigers are hard to differentiate sexes. My two male A. mavortium have had VERY swollen cloacas since I first got them a year and a half ago. It is very obvious with them, I'd say the cloaca are swollen to at least 3/4 to 1 inch.
And my male tigrinum also has a swollen cloaca, but not nearly as obvious, probably because he is only a couple years old.
And after the recent post about confirmed tiger breeding, I have a feeling there will be a lot more success with it, hopefully in the US, too.