Yea, I don't know about thatbarefoot stuff SoB, but if it works for you...
I walk almost every day, and in hilly terrain, with shoes. Lightweight, but still shoes.
Before a long distance walk, I step up my training somewhat. Last time (before the 300km+ TGO in Scotland), I visited the physio. I did this because last time, I was pretty sore after finishing 14 days solid walking and didn't want a repeat of that pain. The Physio did a full body muscle strength and endurance test on me in the practice gym. The result was some take home leg and back balance and strengthening exercises (basically double and single leg squats, and some bridging) and a regular Pilates session. I did this on top of my regular program which I extended closer to the walk with a heavier pack and a bit of running for extra cardio.
During one of the tests, I exceeded the time expectations for holding a core tension test by at least double and had an audience of physios by the time I gave up! Got a bit embarrassing with all the attention
The end result was that I finished the walk in great shape with none of the soreness I had last time. I could have kept walking, but I was at the coast and I'm not much of a swimmer

The point is that I think the best training for an activity is that same activity supplemented by some strength and flexibility exercises.