BCIs stay smaller than BCCs, and males tend to stay much smaller than females. I have an adult male BCI red-tail that is around five feet, and does not have nearly as much girth as my adult female BCI does. You could also look into dwarf boas, for example, Saboage, Pearl Island, boas. They top out at around five feet and do not have much as much girth as a common red-tail boa. BTW, none of my boas are aggressive in the slightest.