Hey Adam,
How much weight can you carry with the approach shoes?
Good question. I think it depends on the shoe. My shoes are pretty comfortable, but they aren't the most comfortable I've worn. However, they are sticky like hell. I love that. I'd guess my pack to be under 20 pounds with food - it looked pretty full, but it was a lot of lightweight bulk like my closed cell pad, down jacket, etc. This is a long trip, so consider the pounding your feet will take over all those miles. Ankle support really wasn't an issue, just proper support underneath and padding, I would say. That's what will hurt you towards the end of the trip.
