If there's an issue, it will be with the shock at full extension... when it "pulls" on the mount. With no webbing (flange) to support the lateral load it may flex and ultimatley break the mount plate where the 90 degree area is that you cut out. That's the purpose of the flange all the way around the mount plate. I think you would have been better off switching left and right plates and turning them up-side-down (I think?), allowing the axle pad to "cup" in the mount. You would have gained the same reach on the u-bolt and not compromised the flange strength.

Jeff!