Remember, or imagine if you never had the experience, that time you were in college in the tiny dorm room, forced to share your space with a complete stranger. No matter how innocuous and agreeable your dorm-mate, there would still come times when you were sick to death of each other and needed to get out for a breather.
Now think about how you would feel if you never had that option of leaving, you were in the same space with the same person 24/7. Now remember that humans are social creatures who naturally seek out company, and that snakes are not.
If you're concerned about space, I would advise switching to a rack system if you absolutely feel you want/need more animals. The other option is don't get more snakes. You need to be able to provide optimal care for each of your animals to maintain their health and well being, not just what is convenient for you.