Well, the most important thing then is that you are learning from your mistakes. I have made plenty along the way, as have others on this board, but as long as you learn from it, there is no such thing as a bad mistake. Really, I like that you tried thinking outside the box and trying different construction techniques. It seems like you just need a little more experience to figure out the pitfalls and where to compensate to make your ideas work.
One thing to consider in the future, is being carefull about uncontrollable feedback. With large chambers, and a large soudhole like that, it seems like it will be prone to feedback. I am not terribly familiar with the design concepts behind semi-hollow or hollow bodies, and what is done to help prevent feedback, so that might be something to study on.