I figure that each device is using max 60W so in total this would at most be 1800W. If I can run a 3000W kettle then thee shouldn't be a problem but I am probably missing something?
You are not missing anything power wise, your arithmetic is right, the only practical difficulty I can see is providing 30 AC outlets for all these adapters. You can get power strips which provide 10 or 12 outlets each, maybe more. The one in the picture has 12 outlets, a surge protector, and costs $11.95 from Americord