painting inside the trunk

Most all the bare surfaces on the bottom side of my Barracuda are coated with POR15 too. It's held up there just as well. When POR15 (or any of the other similar products) is applied correctly over a rusted surface it's almost impossible to get off. As for a breach, much less likely to happen with it than a conventional coating, you can beat on it with a hammer and not make a mark.

The thing that sold me on it was my cellar bulked, its metal and the stair insert in the ground is also metal. Every year I had to wire wheel and repaint the dam thing. I tried every rust preventative the hardware store had to no avail. Almost 10 years ago now I knocked off the loose rust, painted with POR15, primed with POR primer and painted with red enamel. I haven't had to touch it since and it takes quite a beating.