I sink a lot of CV's. I've been asked to sink a lot of CV's by my fellow Bishops. I enjoy it. On the "dive-bomb with B17's" bit, I agree, it's a bit cheesy. BUT, planes diving in that low are easier to go after and kill.
CV's are defendable, even at 8K, which is where you will find my B26's coming in at to sink them.
I would suggest that if you want to keep your CV floating so that you may continue to have fun in fighters, bear in mind that someone invariably will come in on an attempt to sink it. Killing bombers are kills as well as killing fighters. It doesn't take much for the CV defenders to fly defensive cap over the CV and intercept enemy bombers. I know this works because I've gotten my butt shot down by the best of them, either by good ship gunnery or by those that choose to think ahead and watch for bombers.