You didn't ask, but I feel the need to share - CX don't move over unless you physically make contact and force them to move. I used a gravel rake to move them over so I could stir their mulch when I raised them in a covered run. I'd worry about them getting their toes stepped on when moving a tractor, and even walking up on and off of a 2"x4" is a chance for them to trip and fall, so try and design it so that doesn't happen and move the tractor somewhat slowly - they literally only move when forced, and you don't want anyone getting trampled. I had a literal ramp in the center of my brooder so the chicks could safely get over a 2" raised area in the center (where i'd joined two dog crate openings together).
Also always look before you set anything down in the brooder - egger chicks will run out of the way of hands or objects coming at them from the sky, but CX don't do that. They will stand there and be squished unless you physically push them over first. Unfortunately I know this for certain first hand and will never be making that mistake again.
I raised 25 CX in 150 sq feet, and literally had to herd them over so I could fill the food, water, and deal with mulch. They kept wandering back over to me, and are very ungainly. Very docile through processing age, and easy to catch because they're slow. All you need is two people or one person and a towel or rake. I could do it by myself, but it was easier to do with a buddy.
At 9 wks old I had one female extend her neck a bit to reach up to get at the 5 gallon bucket horizontal nipple waterer I had up on a cinder block. She was jostled by other chickens, lost her balance, and fell over on her back. She must've been 10 lbs live weight at least. She was so large in the breast and ungainly and her wings were small and useless and she couldn't right herself. Luckily I saw that and flipped her back over, or I'd shortly have had a dead chicken.
Good luck!