I just don't think TC is either remarkably intelligent or prepared. He picks up ET and she leaves her backpack behind. He leaves a note which alerts his wife immediately. He dyes his hair as if that is a surprise move.
Something just occurred to me about that. There's been speculation that he's been putting out a false trail of disinformation. Could that bag have been left behind intentionally? Perhaps it was meant to be found by the police/family, but instead someone stole it?
There might have been some (false) clues in the bag as to where they were going - travel brochures or maps, for example.