thinking out loud--
We know that for 2-3 nights after the disappearance there were radio signals, presumably coming from the Electra. We also know that on Lambrechts overflight on the 9th, they reported signs of habitation. We also know and assume that he didnt specify where those signs were. Reef ? 7 site? beach? lagoon?
I propose that from july 5 to july 9 (4 days), Amelia and Fred did not go to the 7 site from the reef---3.5 miles, on an island they had not searched. I propose that they may have been inroute, and some of that evidence may still be there. Campfires, personal effects, etc. I'm thinking that after 3 days around the Electra, without some provisions, they may not have hiked the 3 1/2 miles and found the 7 site. but were exploring as they could. Hungry, and possibly injured, as well as NOT knowing anything about the island, makes me think that they were exploring. I think, maybe, that befor the landing, they could have made a pass over the island, to briefly check it out. But, flying over it, and hiking it, are 2 different things. As the expedition teams have said, the dense underbrush would have made hiking the jungle very difficult. Walking the shoreline, may not have revealed much. Same with walking the lagoon shore.
I guess my point is, during the previous expeditions, have you found evidence of "habitation" (other than the colonists) between the probable landing site, and the 7 site? 3.5 miles is a long hike to nowhere. Today, we hike with a map of somewhere that we want to go. They were hiking into the unknown, on an island in the middle of the Pacific. Totally different scenario. Maybe between the 2 sites there is more evidence.