Go used and go a little smaller than you think. The Speed isn't that heavy, especially if you are using a normal type lens. No sense killing yourself over a tripod. That takes the fun out of overland hiking for your art. Don't go with a ball head, they are too unstable until you get into large (and heavy) sizes.
I use an old "Star" for my Speed. I won't handle the Deardorff or the B&J 5x7, but the Speed works pretty good on it. And it weighs 1/3 what my Bogen does.
tim in san jose