They had the adult male breeder there too. He had to weigh half as much, if not less, than the female. My guess is he was 1-2FT shorter and 1/2 the girth.
Male BCI are usually much smaller than female BCI. Key word there is usually.
Richardhind1972 is correct that if you want to stay small, you need to go with a dwarf locality Boa.
Also, from what I have heard and seen, that female Sunglow in the picture is about right for an adult female BCI, give or take.