I'll wade into this conversation knowing that discussion of electrolysis and galvanic action begins to sound more like a fight over which religion is better....
but here goes...

I can remember 15 or so years ago when I had to rebuild #3's rudder, I also had to replace the rudder shaft.

The original rudder was the two-part shaft style with a prop cutout.
At some point, a previous owner had put one of those flat, round zincs through the back of the rudder, not touching any of the metal bits.
At that point in time, it was ~ 40 years old or so.
By that point, the upper rudder was looking very pink-ish.

so I made the decision to replace the 2-part shaft and broken mahogany rudder with a single shaft and a plywood/fiberglass version of the same shape.

I'd have to go back in the archives here, but my recollection was that I agonized over which material to get for the shaft, in part because the upper part was looking very pink-ish.
Now, it had little to no cathodic protection during that entire 40 years, so that should not be surprising for a 40-year old hunk of bronze with no cathodic protection.

When all was said and done, I ended up re-using shoe and using a bronze (of some sort) shaft. and then put a zinc on the shoe. I just drilled a hole all the way at the bottom from port to starboard and put two tear-drop zincs on either side, with one big thru-bolt.

So while I appreciate all the discussion of which bronze is best, etc, I think that all of that can be essentially obviated with any sort of protection.

As to the stainless-bronze issue, again this seems overblown. almost every boat out there with an inboard engine has a stainless shaft and bronze prop. so we just slap a zinc on there and call it good.

As to the issue of zincs eating the mahogany, I can see that because the manner that an anode helps is by creating OH- ions which are very basic on the pH scale. bases are quite harmful to organic material (think Draino). But as long as there is any sort of space between the zinc and the wood, it should be fine. The issue is when you trap the OH- ions at the wood (like under a zinc bolted to the wood). so don't put your zinc on that way.
The "grouper" or my zinc at the shoe avoids it, and I'm sure there are other creative ways to accomplish it.

Just as a bit of perspective, Ariels and Commanders both went into service about the same time as the USS Enterprise.
She has since been retired....
In that time, almost every piece of metal touching the sea had been inspected, repaired, or replaced at least once, often many more times.

If you have to replace a rudder shaft every 40 years or so, I say that's a "win".