His plans do get you thinking, it's a very good jumping off place for building designs. However I agree with your wife - I wouldn't cook in a separate building, heck I may not even cook with the kitchen as part of a great room

But I do see the advantage to avoiding the building permit.
I have no idea about how he does his roofing on that much pitch, but you could Google attaching corrugated roofing and see what pops up. . . . .