Have you considered getting your car rustproofed? I'm up in WNY and I've seen what this salt does to the cars here. Given the build date of my car, I didn't have too much time to think about it so I jumped on getting it done.
Also, what is this paint protection you're talking about? I'd like to keep my car as nice as possible considering it lives outside and is my daily driver.
I am considering something for the undercarriage, but I'm not sure what.
The protection I'm referring to consists of two components. Paint Protection Film (or "clear bra") is a self healing adhesive film designed to primarily protect against damage from rocks and sand. I had the "full nose" covered, including hood, bumpers, and A-pillars. I also had the rock rails (or whatever that lower area under the doors is called), wheel arches, backs of the mirrors, and rear bumper covered. Once the film becomes too damaged from impacts it can be replaced, typically 5 years or so on a daily driver. See that patch of plastic near your rear arches? That's a crappy piece of paint protection film from the factory.
The second component is a "nano coating". Think of this as coating the paint in acrylic nail polish. If you have film it goes over the film because the surface of the coating is so slick the film wouldn't stick. There are several types, but Ceramic Pro seems to be the best at the moment. I've had 9 layers of their "9H" permanent protective coating applied to the paint (which must be perfect prior to coating, since the coating can't be removed without grinding it off) followed by a less durable (2 years vs lifetime) top coat of Ceramic Pro Light, which increases gloss significantly. Beyond a fresh wax shine.
What does this do for me? It means I can quickly wash the vehicle with my pressure washer and it looks like it's been freshly waxed to perfection, day after day. Brake dust sprays off. When I drive in the rain, it barely leaves any dirt on my white SRT. It's unreal. I've never seen a white vehicle with this much gloss. The original paint is safely protected from acid rain, bird bombs, salt, and the constant bombardment of sand that hammers your paint. It won't protect against a rock impact though, which is what the film is for.
They use different Ceramic Pro formulations for glass, metal, plastic and leather. Black plastic (looks super deep and rich, without any greasy residue, and is guaranteed to remain so permanently. Glass behaves like it's been treated with rain-x. The glass treatment lasts about a year. The leather, ultrasuade and plastic in the interior look 2 shades blacker than before (I saw it in process, the difference in color of the leather is significant). It doesn't change the "feel" of any of the materials inside.
Maintainance of the lifetime warranty require an annual "inspection" by the installer. What this really is, is a $199 procedure in which they decontaminate the surface of the vehicle, and "refresh" the coating with a single fresh layer to restore its hydrophobic properties and gloss to the way it originally was.
My SRT looks better than it came off the lot, and keeping it looking perfect is a breeze. Search youtube for Ceramic Pro, and Google "Ceramic Pro forum" and you'll see it's a treatment owners of high end cars do frequently and are generally as pleased as I am. I liked the results so much I had my Wranglers done as well. No more waxing. What a relief.