Wow love this idea.
Here's a thought. In the interest of preserving the stock look in the rear, why not use the original bumper ends modified to accomodate the reinforced spindle mount.
Love this design and ingenuity!!
I believe this has been done, but welded on and not bolt-on. So this maybe an idea to explore.
There were additional reasons for going with an "all-metal" bumper end. One being that I could actually use it as a step. I incorporated a large radius indent in the flare to put your one foot on, but in actuality, it came out to be too close to the body. I also added a hole to mount an antenna and as you see, a floodlight.