Small snake for 2 foot enclosure?

[Missy]

Hi
I have a precision cage that measures 2 feet long and 20 inches wide and around 14 inches high.
I recently put my High white Ca king into a 55 gallon tank and looking for a smallish size snake that you actually see here and there that wont outgrow that size cage and be happy there not cramped.
I have a few choices African house snake (male)-New Mexican milk-scarlet kingsnake. I dont have any preference for any type snake but not venemous .
I prefer a snake that you see and doesnt hide 24/7 any suggestions ?
The cage is nicely decorated with climbing sticks,hide areas and would like a snake that would enjoy this here and thee my CA king was very active but got big so put him in 55 gallon tank.
Thanks.
Missy