the G28 rear bumper is 1.5" give or take a 1/4" to long on the sides , so 2 choices are available ,either cut the rear wheel well opening in the top middle to add 1.5" there an behind the rear wheelwell opening remove 1.5" an glass it back together ...not 100% sure if the angle of the body line where it bolt back to the rear Quarters will need changing but if you make it this far the rest is easy. Other option is to move the whole wheel well opening back 1.5" ,this will require modifying the VERY rear section of the drivers side an passenger side scoops
please photo shop guys Read this 3 times an make us a photo drawing example of the side of the G28
Maybe AD John will let you get a Rear bumper at material cost to do this an if it look like a easy fix , he can sell more rear bumpers ,who ever do this will be The first to render a solution to the oversized G28 rear bumper .....waiting on the forum photo shop person to make us a drawing with both options.