If you live anywhere where corrosive road salts are used you must rust proof, if you own your Jeep, if it leased, well you can forget it, that's one reason to avoid buying preowned.
I bought the dealership treatment, which is an underbody rust proof wax, which obliges the dealer to repair rust, but I prefer not to have any rust to worry about so I also do an annual rustproofing with an independent rust proofer who makes a few holes in the vehicle through which they apply rust proofing oil. They spray it into all cavities as well as coat the undercarriage and engine bay. If you start with them from new vehicle and apply annually (under $100) they guarantee no rust for the life of your ownership of the vehicle.
Makes sense for me as Montreal bathes the streets with road salts.