Rust Proofing

I'd like to rust proof my Wrangler's underside since I drive it a lot in the winter when MI roads are covered in salt. And I'm sure the underside gets battered in a lot of other ways too... Is there anything that can be sprayed/painted on the bottom to stop and prevent corrosion? ...I just want to keep this Jeep for years to come. Thanks :cheers:

I used this stuff.
http://www.eastwoodco.com/jump.jsp?itemType=CATEGORY&itemID=374
I used it on a rustbucket dumptruck frame and I spot touch the bottom of my Cherokee with it. Stops rust in its tracks and prevents further rust. Eastwood has several other products for this purpose. Cruise around their site alittle, youll find all kinds of good stuff.
For a cheaper, quicker fix, Auto Zone carries a spray on rust incapsulator thats only a few bucks and works well for sealing light surface rust.

What should I be careful not to cover on the underbody with this stuff? I like the ide of just spraying something on without too much effort, so I just need to know what to tape off. Thanks.

I tried to avoid rubber lines but I dont know if it would hurt them or not. I dont recall any warnings on the container about it.