I agree that route would be awful in August, at least it would for me, but I hate hot weather. I would be inclined to go in winter with a bit more southern route if you must keep it to 3000 miles or less. The ACA Southern Tier Route is about 3000 miles and was nice in February. I might ride a lot more on US 90 if I were doing that again.

I disagree with the comments about the south. I found the south to be just fine for bike touring.