Perhaps it's time for the clever people at JPL and other places to design some kind of electric horse. They've designed successful rovers for the Moon & Mars. And we have had horseless carriages for as long as I can remember. Lots of markedly better battery and motor technology has popped up in the last few years, too.
After all, the requirement is only to reliably carry a few hundred pounds a few dozen miles.
Then there is the Llama - which is far better adapted to altitude and easier on the environment.
Why is the horse the only solution?