Well, yeah, you've proven my fears... I have no idea how the insides of the subframes will be galvanised. Zinc will not stick to rust, so we'll see (or maybe not see...).
Those dents aren't dents. That is iron bacteria actually eating your car. Yes, it's true. There is a life form on earth that eats iron (steel). Big problem in shipping apparently. Once the little bugs get under the paint and it stays damp, they thrive and dissolve the metal away. Different to corrosion or oxidation. They also live around deep ocean thermal volcano vents, living off high iron deposits.