This post put the pressure (paranoia) on to install my inline filter, so I did.
Step 1 was to perform the busham bleeding procedure…
https://www.bimmerpost.com/forums/sh...php?p=18425381
…and then start the installation.
(I only had about 10,000 miles on my fluid, after a full flush, and it didn't actually look all that good)
I'll post a detailed install after I modify the BW reservoir with a proper cap/filler neck design.