I've already been taking about 10 mile walks, with a backpack loaded up with 20 pounds using 2 10 pound dumbbells, for a few days now. I include a walk through a park near my home that has some decent-sized hills. It hasn't been tough and after another week of that I'm going to load a 45 lb free weight into the backpack and walk at least ten miles with it for many weeks until I'm used to carrying the weight on my back.
I'm also want to get a large multiday backpack to store all of my gear. From what I've read about them, they distribute the weight evenly through your body so very heavy loads don't feel nearly as heavy. I of course have never used one before so I cannot vouch for the validity of those statements. But if they are accurate, then hauling a large amount of weight long distances is feasible.
I realize that carrying less weight would be more comfortable, but I do not want to have to worry about having to resupply too often and I am willing to carry a heavy load of supplies