Being a Eagle scout I have had a lot of experiance with cast iron. Mostly in Dutch Oven form though (same basic princibles though) Anyway all we ever do to clean them is turn them upside down on the fire or coals and let everything burn out. then just wipe out the ash. It works great.
There was a leader who had a few old and well seasoned Dutch Ovens that we often used. One kid took one home to clean wothout the leader knowing. Well him and his mom decieded that it was nasty and dirty, they spent hours washing it and retutning it to a healthy silver color… The leader was so very upset we all got a lecture for over an hour on how to care for them. I remember a bit, like never use soap, ever.