I did both of our trucks today. If I were to do it again I'd use the shorter struts- on one truck the spoiler supports just touch the roof edge, and on the other truck the hatch edge contacts the roof edge at one corner. That truck has been in a serious accident and the hatch isn't perfectly aligned, so that result probably isn't typical. Still, I'd like some room at the spoiler support, and never really had any issues with the opening height of the hatch- just wanted more, like any good American.
Both trucks took a total of about an hour, using jamb nuts I picked up at the local Ace- forgot to order those with the struts.