That plan looks like it would have a sagging problem. You would need some sort of support partway along the cage.
A cage that size is going to be difficult to manouver and clean. Also, 24" is too narrow in my opinion for a large python. And 12" high is certainly too short, IMHO. An adult python would have trouble eating in a cage that small. Then consider the waterbowl. Your water bowl is going to have a lip at least 6-8 inches high and the four inches of clearance above it would make it almost impossible for the snake to drink well. A larger shallower pan would just evaporate.
I suggest at least making each cage 24" high, at a minimum.
Also, when you start dealing with cages of this size, I think you should take a good look at the commercial cages made by Vision, etc. For large cages, their benefits are clear!
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Chris Harrison
...he was beginning to realize he was the creature of a god that appreciated the discomfort of his worshippers - W. Somerset Maugham