Take it from someone who works/has worked on carbon fiber on a regular basis -- you can't fück up the integrity on that carbon fiber tube if you notch it. It'll take a lot to fück the integrity up on that thing. Besides, carbon fiber is easy to repair, IF you know how. :))
If it's "real" carbon fiber, you can grind it off to form a notch very easily, but given what you have, I'd notch the front sight. Tom would just take a hammer to it and beat it into submission.