I ran into this too. Luckily a good friend of mine worked at Bilstein and was able to remove these ends (they screw on) and put a set of standard ends on. He had special clamping blocks that held the shaft as he put them into a 12 ton press. Once the shaft was clamped to not rotate, he used a big wrench to remove the ends. Biggest thing is to not score the shafts.
I did this as I wanted to use the outer reinforcement brackets that CPP sells.
Here is what it looked like when done.
That said, I still have the old parts and could test out grinding the rivet off and seeing what is behind the washer, if you like.