There's been a lot going on in the past few weeks, and some of it has involved walking along a trail in Scotland with my brother. We went about twenty miles in two days, which was nice, but it doesn't quite match up with the one walking speed reference point I had-- the Roman army's full pace marches of roughly twenty miles a day. We didn't set up basic defensive palisades each night either.
I hadn't anticipated getting tired from walking, and the limiting factor for our pace turned out to be pain rather than being out of breath. With some training, I suppose, a much faster pace would be achievable. Camping regulations vary, of course, as do regulations on cutting live wood (without which constructing a palisade would be difficult), but I'm confident the Roman march is not out of reach.