So, in order to align the rear tires, I have to drop the back end???
No, maybe you didn't get correctly what I wrote. On stock height to a lowered height under 2'', camber and toe will remain into spec numbers. It's when you want the cube lower than 2'', you'll get neg camber and eventually get camber wear on the tires.
For all info on rear suspension, look at the pages of the cube fsm on this link. On page 6 in the first lines, it is written that camber, toe-in inclinations angles cannot be adjusted. On last page,13, you got all the number from minimum t maximum specs.http://www.nicoclub.com/FSM/Cube/cube_09_fsm/rsu.pdf