The Pickett's Charge field isn't really too hard to walk. They usually have paths moved across, but it isn't paved or leveled, so it would be difficult for someone who has difficulty walking. You can't really get a good idea of the swales and the distance unless you walk across sometime.
Did a little (impromptu) experiment last year: I was there with my teenage boys. And they really wanted to "charge" from the VA monument which was the position of those troops back then all the way up Cemetery Hill. Charge is the kicker here. In every "historical" (or not) re-enactment I have seen of that, it was not a charge. It was a s-l-o-w march. My kids did charge on that terrain and they fell about 3-4 times each while doing it before they even reached the road (that is there today, and that is about 1/3 of the way up the hill.)