David-
Maybe this isn't quite what you're looking for, but here is what I have done:
I have the 6" KC's and was originally going to mount them to the factory bumper, but it didn't appear that I would be able to get the clearance between the back of the light and the grill. I then made some brackets which would extend forward about and 1" but I was afraid that the lights would be very vulnerable to being bumped, etc. I finally ended up buying the SmittyBilt Outland Sport Bumper Guard. This comes with six holes made just for this purpose. It is well made and gives the lights some added protection.