Another possibility is you could put a transfer switch before each panel. Such as 4 200A transfer switches if you only had 4 200A main panels. Not saying it's a better way just another option. I don't know how the service is set up and land availible but something elce that could be done is multible generators. Such as 4 18 or 20's hooked to each transfer switch and panel. Maybe bigger for the mechanical panels and les if the panel is a light load. Figure also for the chunk of money the customer is paying they will expect no excuses if they lose power. By having more than 1 gen and transfer sw their will be less chance of a complete failure if a problem dose arise. Also the install may be much easier. Such as not needing a cement pad, crane, over weight permits for the trucks, etc. That's $1-2K less right there. More future maintence also for you. You could even sell this idea to the HO as better being better because all the eggs were not in one basket.
One thing that I wonder is if it can take the A/C load if several compressors were restarted at the same time. Kinda makes you wonder what they came up with the orignal load calc's.
The gen rep you spoke with did he get any details about the square feet, A/C sizes, electric heat, pools, or what ever elce is there? Just kinda wondering if it was a sales person that just guesed it would be good. If it was Generac/Guardian I would not have much faith in them, especialy if it was the sales dept.
