Wow, that is pretty involved. But I know how it is. It reminds me of the sort of stuff I did to remove the crank pulley bolt on my old Honda Odyssey for a timing belt job. I did not have such the array of tools I have now, and used ropes, strut compressors, etc., and 6 hours later it was off. And the BMW crank bolts have much higher torque values and notoriety.
On the locking pin (supposedly only for alignment, but ...) I found the following which was pretty convincing, from a guy who has written a lot of cool stuff on these M54 engines:
https://forum.e46fanatics.com/showthread.php?t=953907
That pin has a pretty good radius arm - like about 10 cm, which I think helps it to work. He detected some slight deformation after doing 6 loosen-tighten cycles.
So I went ahead and used the locking pin. I just need it to last long enough to get the bolt reinstalled later, and it's good enough for me.