River City Sol, I installed my SQR2 system while waiting for my diffuser & it really doesn't look that bad. Mine was that way for a couple of months & I got no "ill" comments about there being no rear fascia. Go for it, you'll love the look of the SQR2 on the car even without the diffuser & when you get it you'll love it even more!
Realignment was minimal,
take your time installing it & you can align it pretty close without the diffuser, use the bolt hole in the black styrofoam bumper piece for centering it.