My car has some heavy rust corrosion within the side cowl areas down low and some tiny pinholes in an area completely hidden by the fender when it is installed. I can feel the rust by reaching in thru the kick panel vent holes but otherwise very inaccessible to knock down with a wire brush or other abrasive. Considering the limited visibility of the location I do not want to cut out and replace metal. Was thinking about gloving up and just getting in there with a brush & POR 15 as best as possible. Only concern is I usually mechanically remove as much rust as possible before POR which I can't this time. I'd be applying it on raw rusted surface. I also like to use Picklex 20 on rust before a coating like POR or Zero Rust, but again, tough to get in there to spray evenly. Any other suggestions to treat concealed/hidden area to halt the rust?