Thanks for the replies. We will actually be making these on a campout with 16 Junior Girl Scouts and 5 or 6 adults. I think we will be "burying " them in the coals as opposed to cooking them on the grill rack, because there just won't be enough room for all the food on the rack. I know we will either have to have a very big fire or else use a couple of fire rings, but I think we will have two or three rings available as our group is a large one.
I don't know how foil wrapped differs from non-foil wrapped as I have never grilled whole potatoes, but I do remember that I LOVED the ones my dad made. I'll have to give the sea salt method a try sometime when we grill at home. Thanks to everyone for your help!
Less rhetoric, more cowbell!