An interesting thought came to mind recently.?? Durring book 1 2 the Gaang has had no real reason to hide their identity as the Earth Kingdom and Water Tribe are allies in the war against the Fire Nation.?? They are freqently welcomed with honor into any town and never really have any big problems with the locals (discounting that crazy place in Avatar Day)
But what happens when they reach the Fire Nation??? The creators have said that everything in the Fire Nation is a big propaganda machine to keep up support for the Fire Lord and the war.?? Everything is in the nations colors, red and black.?? I would think Katara and Sokka with their blue outfits and Toph with her green would sort of stand out like a sore thumb.?? How else would they be able to fit in unless they adopted some traditional fire nation clothing??? Even an outfit change of course wouldn't completly hide their identities as Zuko's scar and Aangs arrow are also also big hints.?? On top of that, Appa would also be a huge target and would again only serve to attract a huge fire nation force wherever they went.
So unless they really do have the backup of a large Earth Kingdom/Water Tribe army slowly moving into the Fire Nation (I doubt it, the eclipse would only last for 1 day and would not provide enough time to completly turn the tide of the war...not only that but I can't picture the Gaang staying with this huge army the entire season, they will have to interact with fire nation citizens at some point) how might they be able to sneak around?