I think the lack(if there was none) of a W/B and trim setting point will be in the final report, but not as a definitive cause, and will only be one of the contributing factors. Given the swings which seem to introduce the left seat taking control, I can't help but also consider the polar moment of inertia of the mass(meatsacks, baggage) behind the main gear. Much of this seems to contribute to reasons why the tail was not up by the apparently prescribed 40kts, as others have indicated(I have no time in the C7, but plenty of TW time in other smaller stuff).