What do I need to make IR beam work with long lenses?

Probably a dumb question but last night I attempted to take some shots in the dark of an Owl with my 400 f5.6 lens. I had my 580 EX ii mounted on my 7D but I quickly noticed that the IR focus beam hit the lens and not the subject I wanted it to focus on. I had to switch to my 70-200 f4L to get it to work and even this the beam still hit the front of the lens a little.

Would a flash bracket fix this problem? Just want to make sure before I buy something I may not need. Thanks for the help!