Manfrotto makes a monopod head (#234, and #234RC with quick-release) that's easy to use and adds very little weight to a monopod. It only swivels in one direction, but that's not a problem when using a monopod.
As for supporting the monopod when it's not convenient to put the tip on the ground, you can support it in a fanny pack, like a flag-bearer in a parade. I read about this in an interview with Gold and Goose, a team of English motorsports photographers, who often shoot with a 600 f4 in this way. Manfrotto even makes a special waist pouch for this purpose. If you've never seen the work of Gold and Goose, it's very impressive. Tight shots of motorcycle racers, moving at high speed, shot with a 600mm lens, and you can see every stitch on the racing suit. Hope this helps. Pat White
