Finished grinding by smoothing out the CPP notches a little more...
We came up with and fabricated a custom rear crossmember out of angle iron to hold the air tank. I did a lot of measuring to make sure it wouldn't stick up too high and hit the underside of the bed or a crossmember and won't be too low to show under the bumper...hopefully all the measuremements are right
In this picture the frame is upside down so that's why the bumper brackets are that way.
Here it is welded on. It may not look it due to the notch for the bumper bracket, but is so strong, Jason used that bar to lift the whole frame on his end when we moved it.