What i use as a rule of thumb for closure size is that the tub, or tank or whatever the animal is being kept in should be half the length of the snake. A full grown bp can spend it whole life in a 20 long fish tank and be happy.

With what day breaker said I agree 100 percent. A BP in the wild spends almost its whole life in the tight area of a termite nest and they come out at night to eat.