Not to run this into the ground, but here is one more of the fender above after soaking in the 'bath.' Unfortunately, we had some rain, so everything that wasn't submerged got pretty nasty looking
You can see that while this works on the heavier rust, it is better to knock off what you can by sanding to get better results. The solution weakens as the rust is desolved
Also, this tile cleaner stuff does work well, but seems to have some detergent in it as well, because it foams up something aweful. I might be going back to the previous product I was using if I can find it! I'll fill you in when there is more to update!