Enclosure size questions

[Skulk01]

I currently have a young kingsnake and plan on picking up a ball python at some point. The king is currently in an exoterra medium low 24x18x18 and he's still fairly small so should be good for a while.

My plan is to build a set of enclosures (1 for the king, 1 for a ball python, and 1 as a just in case I pick up a 3rd snake down the road) that can stack on top of each other.

Because I want them to stack I'd like them to all be of a uniform size. I'm thinking 24" deep 24" high (I know that probably seems taller than necessary but Ash has shown to be a bit of climber so I'd like to have some vertical space to work with). The part that I'm stuck on is the length. 36" would be ideal for placing in the house as I have several places that would accommodate that size perfectly, if I push it out to 48" I do run into some issues of where to put them, but that seems a more ideal length for the snakes.

Would a king and a ball python be ok in a 36x24x24 enclosure (with some shelves and/or branches for some room to move vertically) or is 48x24x24 the absolute minimum I should be looking at?