Ok, so you have a "space restriction" I imagen that is going under the CT. What I would do is put a 18x24 On the side of the cabinet and run 4" from the CT to the 18x24 and 2" pipe to each of the Panels.
Then into the 18x24 use four split bolts big enough to fit in The big wire and two of the 3/0 for the panels. and feed your Panels from that.
I've done this in the past, and found out that it will pass inspection and is more cost efficient.
