Removed the frame from the dunk for the last time today.
Yes, more rust was removed, but it appears that to be truly effective on the inside I would have to fabricate a rather intricate system of anodes.
Without that electrolysis remains very slow if it is doing anything at all.
There are separations between layers of the steel due to heavy scale, similar to frost heaves.
This is mostly inside and there is really no practical way to repair it.
Big disappointment as another owner of several Europa's was impressed with how sound it appeared to be when he looked at it.
The 'rule of rust' remains, it is always 3X what you can see.
I am going to go ahead and complete the T repairs as a practice exercise.
But there is no doubt I am replacing it.