Maybe you don't have your own air compressor and impact wrench. (the second best big-ticket tool I bought after a hydraulic jack and jsck stands) Borrowing or renting something might be cost effective.

I just zip off/on that nut with a 24mm deep well socket. Just make a special note about how many threads "on" the nut is before you remove it. This will help go get the new one on tight enough later. (I never found a torque spec for this nut in Bentley's)

As for the strut tube cartridge nut, I loosen (LOOSEN, not remove) it using an 18" plubmer's pipe wrench. After I have compressed the spring, lowered the strut assemly out of the car and removed the spring, then I have full access to remove this retainer rest of the way. The wrench slides in between the springs while the strut is still inthe strut tower. Take the steering to lock position to get resistance for your leverage for breakig it loose and for final tightening.