The smallest tripod I've used was a Libec 22, but I don't think it gets quite down to 24". Probably 3 or 4" more than that. Gitzo makes a small carbon fiber system but I think it's single stage and doesn't fold down any shorter than the Libec. There is a lighter weight Libec, the 20, but I don't know anything about it. I would want to stick with a real fluid head if at all possible. There's also a Slick/Daiwa (something like that) that's around $500 that is fairly light and allegedly decent, but I haven't seen it in person. Gitzo has always seemed the best thing available in the lightweight department. The Libec 22 specs say it's good for uup to 8.something pounds, but a Canon XH A1 is just over the top for it, I found. Like all the cheap ones under the Libec 38, it has the dreaded bounceback at the end of a pan, but it's controllable with care.
This Bogen system seems to be within your specs:
http://www.bogenimagingstore.us/serv...n-Fiber/Detail But it's another one I know nothing about. You'd have to give up ball leveling. I did a little research on small systems when I was into small and light for some shooting. I ended up with the Libec 22 but later got the 38.