Are your 30 CX going to have any forage options?
Are you restricted by zoning (or neighbors) on where you can have them in your yard?
Do you have enough grassy areas to accommodate their droppings left behind?
I'm just finishing up 25 Freedom Rangers on 2 acres in greater suburbia. I can tell you, these critters grow SO fast - you've got to have your final set-up completed before getting them, or else you'll be constantly behind! I have been behind since day 2!
I had our 25 in a 4'x4' brooder box in our barn. That lasted about 14days well, had to put a lid on it by 8th day, as they were flying!
They then moved to a 8'x8' PVC tractor on grass. That lasted for another 2weeks. Was having to move the tractor every 4-6hrs, as their droppings were too numerous and killing the grass.
Then into a 50'x20' run (with PVC tractor acting as coop) - and having to move the tractor (still!) around the run, as dropping problem only intensified! Ewww.... (We have heavy predator load here, so letting them 'free range' just means 'free lunch' for someone other than my family. They have to be protected in a run...)
Whatever you're thinking of building - build it bigger than you think you'll need. I know Salatin does his much higher #'s - but I'm not sure how to make that work in reality.