I’ve had good success harassing a Star Destroyer with Corvettes. The key is to take advantage of Speed 4 and the extra turn maneuvers allow to race past and get behind. Not likely to take it out, but the great defensive strength of the SD is the ability to shift shields so hitting the shields from behind will wind up reducing the shields somewhere else. At one point I was literally flying circles around the thing. I think I was on my 3rd orbit before a miscalculation left me square in its front arc at black range and I went poof.

If one of the simplifications was removing obstacles and objectives, then IME that will give advantage to the Empire. The Rebels have superior maneuverability in most Wave 1 ships and I’ve found that means obstacles are your friend and the location specific objectives are easier to score. Without those the Empire can slow drive the SD through the middle of the board and, yeah…that’s tough to take down. But then its an SD.