Anyone replace their master cylinder?

[Stewbie]

I'm replacing the master cylinder on my 128i automatic. It's a pain because there is very little room to work in there.

To remove the old MC, I drained the reservoir as much as I could (which wasn't as much as I would have liked because I couldn't figure out how to remove the filter "cup" from the reservoir and didn't want to risk breaking it), and then removed the reservoir from the MC. That made it much easier to get at the lower mounting bolt for the MC.

I test fitted the new MC before bench bleeding (without the reservoir), just so I knew how to twist and turn it to get it back in.

As per the E9X Bentley manual, I also loosened off the booster mounting bolts inside the cabin so that the booster can wiggle around a bit and make it easier to remove/install the MC.

I attached the reservoir to the new MC and bench bled it. Then I plugged the outlet ports with some threaded plastic plugs that came with the MC.

With the reservoir attached to the MC the twists and turns I learned above don't work. The body of the reservoir bumps up against the plastic panel that the booster vacuum line passes through. So I removed the plastic panel, and then the reservoir bumped up against the metal panel.

So I'm wondering if anyone was able to reinstall their MC with the reservoir attached, and if so how?

(After bench bleeding) An alternative would be to drain the reservoir, leaving just a thin layer of fluid at the bottom, then remove the reservoir. As long as you don't take too much fluid out of the reservoir, there should still be fluid up to the top of the grommets that the reservoir mounts too. And if so, removing the reservoir shouldn't introduce any air into the MC bore.

The new MC came with plugs in the grommets, so you can now use the them to plug the top of the MC so no fluid can spill out. With all of its ports plugged, the MC can be installed on the booster. Once the MC is secured, the reservoir can be attached to the MC.

This could introduce a little bit of air in the chamber where the grommets are, but that chamber is separate from and above the MC bore, and is open to the reservoir. So any air should purge itself by simply rising to the top of the reservoir. As long as no air is introduced into the bore, then the MC should be fine.

Is my logic sound, or am I missing something?