Alluding to what Deborah also mentioned, I believe the T8 enclosure from Animal Plastics does offer a divider as an option. From my research, people who have them say they sort of "snap" into place and stay where you put them. Also, as there is not a defined spot for the divider, you can essentially create as small of a space as you want, and then move the divider as the snake grows.

Something else to think about... if you don't have space for the tank now, will you have space for it later? The longer you have the enclosure and the more time you can try/test the heating and humidity, the better off and less stress you'll have later. I did NOT take this approach, and I regret it.

Just my opinion...