For the most part, I get my projects done, start my own in areas where I know there is pain, and advocate for other projects/solutions when I think they're applicable but I'm too swamped with my own work.
It's an issue I've been meaning to bring up with my supervisor ("So just how do I fit in? What's next?"). Is a frank discussion with your CTO out of the question?
To me most of the boxing in is done in your own mind. In my last corporate job I was a team lead who never touched the code. I was supposed to go though my manager for stuff, but he was the problem. I learnt to go straight to the CEO - most of the time the 'open door policy' isn't just lip service.
Many people face the problem in their careers that they think there is a stuctured hierarchy where you can't jump levels for problem solving, initiative or anything like that. So do stuff like that. Your job is really to make the company run as well as possible, whether that is coding or leading changes that need to be made. Staying in your box really means staying in a box that someone else has designed for you, and being successful means spreading your influence by whatever means. Just don't be an a-hole and treat everyone with respect, even those who disagree with you.