We in the film business would suggest what is called a Mafer Clamp. It is designed to clamp onto something just like that. Add a Spud adapter and you can mount anything to it. Look at this:
http://www.filmtools.com/suma484moand.html.
Google "mafer clamp" and you'll find other stuff as well. Look for Matthews Studio Equipment also. Good luck.
http://www.filmtools.com/suma484moand.html.
Google "mafer clamp" and you'll find other stuff as well. Look for Matthews Studio Equipment also. Good luck.