Sounds like they had one of those travel backpacks that had little wheels designed for rolling it around airports and hotels.
It seems that someone someplace might invent a backpack "cart", so that on smooth trails, one could roll it along, so you wouldn't need to carry all the weight. And when the trail gets rocky, strap the whole thing on and carry it.
A frame and wheel or two from one of those baby jogger carts might be a good thing to start with.
I keep wishing I could come up with something, since my significant other is not in the greatest shape for carrying a load, so if I could haul a big load assisted by this cart, then getting us into the backcountry might be easier.
...Llamas are looking more and more interesting, too. :-)