I use the Nikon 80-400 and have had good luck with this "homebuilt" solution. It is a Bogen swivel head and a kirk or RRS clamp. I then attached it to a fairly inexpensive Bogen monopod. It was not my idea, it came from the RRS site:http://reallyrightstuff.com/projects/index.html
With a monopod a ball head is not really needed (can cartainly be used) as the single leg can pivot on itself very easily. The single direction (for and aft) Bogen clamp is easy to adjust and the entire thing is doe not weigh much at all. I used a stainless steel bolt from a hardware store and lock tight to secure the commection of the swivel head to the clamp. I had the clamp and the monopaod already si gambled on the swivel when I put this together but it reallt does do well with the 80-400 (mounted on the lens) I use VR "on" with this setup.