Yes the circlip can be moved to a higher setting to raise the rear.
Thats what its there for.
I would not worry about the CV joints , the diff output flanges slide in and out.

Sport struts or struts for lowered coils are made with a shorter piston shaft.
To keep the strut from bottoming with the lower coils.

Sport struts alone will not lower a car.
Although they might keep a stock coil from expanding to its maximum free lenght.

Teaguer