Hard to choose one

[bcr229]

I was doing some reading up on them. And the one thing I can't find a good answer to is how big they get... I've heard 3-13 foot and 9-10

The size varies by locality. Something like a Sonora or Tarahumara BCI locality female will not outgrow a 36"x18"x18" enclosure, they top out under six feet and the males stay even smaller.

Another option, assuming the enclosure is truly for reptiles and can easily retain high humidity, is a rainbow boa.