Complex sentence: A 1994 report claiming that a group of Boy Scouts had done so twelve years earlier has never been adequately documented and is considered highly suspect in most hiking circles (see Appalachian Trail).
Split into simpler sentences: A 1994 report claimed that a group of Boy Scouts had done so twelve years earlier, but these claims have never been adequately documented. Therefore, they are considered highly suspect in most hiking circles (see Appalachian Trail).