Building something like this that can be pulled by a pair of goats (or a pony, or even a couple of sheep or big dogs) would work, too. Four wheels -- a wagon, rather than a cart -- with pivoting front wheels, is even better, because of what Toosh said -- with a cart, you have to be much more careful about weight loading. Too much in the front is going to put extra weight on the person or animals pulling the rig. Too much weight in the back could lift the puller(s) up and off-balance them. On four wheels, balancing the weight isn't quite as critical because the weight is resting on the wheels rather than on the puller(s) (nor is it going to lift them up off their feet).
Another thing to consider is slowing the contraption on a downhill run. Brakes. Someone at the rear holding it back. Breeching in the harness. Or a combination of those things.
I've been trying to figure out just how large a conveyance would need to be in order to hold our essential supplies. I *think* a 3' X 5' wagon with a covered-wagon canvas top would work (using SketchUp modeling of the wagon and the items that have to fit). Of course, there are things that could be left out to allow the rig to be smaller, but we aren't talking just a short camping trip here, we are talking long-term survival planning, so I'd rather include more instead of less, if possible. Theoretically, for example, we could manage just fine with our skinny camping pads which roll up pretty small. For long-term comfort for these old bones, however, I want my fold-up memory foam mattress, LOL! It's not very heavy, but it does take up space. Daughter's is not quite as thick as mine, but still takes up space. Sure, those could be left out. But if it's all possible to get them in, I want them!
Compensating for the mattresses is needing to carry less food, as long as we have goats in milk with us. We could just about live on goat milk (especially made into kefir). Two or three milking goats per person (or a cow or two for a whole family) would be sufficient. And another goat in milk for each of the dogs.
Don't know that I'm going to build the wagon, but it's been an interesting thought exercise.
Kathleen
