Rust prevention is always a great idea in the salt belt. When I bought my '94 X it already had its share of rust, but each time I take something apart I use it as an excuse to sand and paint the parts I'm working on or near (I have a lot left to do on my X). I bought my 99 Durango new and each year since I bought it I have taken a weekend to jack it up on stands, take the tires off (might as well rotate at this time too) and slide underneath with a wire brush, sandpaper, rust stopper and spray paint. Four years of salt and it still looks almost like new.
By the way, I noticed that all of your pics are of the topside of your X, but the place to worry about is the bottom (frame, suspension, drivetrain, brake lines etc). I'd swear that they design the top to look pretty and keep you content for as long as it takes for the bottom to rot out from under you and send you back to the dealer for a new truck.
Just remember that alot of the parts under there get hot, so you have to use an appropriate paint. I use 500 degree F black engine paint, you could use regular rustoleum on the frame, but why bother. I use 700 degree F brake caliper paint on the brakes and the suspension components near the brakes. I try to get most of the exhaust system with 1500 degree F high-temp paint, but I'm not sure how much good that's doing (seems to be rusting anyway).
The most important thing to remember if you do this is to go to Home Depot, Lowes or equivalent and get a good breathing mask-- not a cheapo dust mask-- one of the ones with the two filters and rubber mask in the middle that costs about US$40. Also get good eye protection. Even if you do this outside, the spray will get trapped around your face while you're under there and there is a lot of nasty stuff in spray paint.
You won't see the results when you are looking at the shiny top of your X, but its nice to know its not rotting away beneath you.
Good luck!
