You can do something proactive, go to eastwoods and buy a few qts and aerosol cans of Rust Encapsulator, and chasis black epoxy paint. Also get some Rust converter.
Wash the underside of your jeep, simple green and a brush and some beer for you works well.
Get it as clean as possible, the use the converter on any heavily rusted areas.
Then top coat with the Rust encapsulator every where, then coat with the chasis black.
Lastly they aslo have a heavy duty anti rust which is a heavy wax coating spray that on last.
You could also buy some of their interior frame coating, spray that inside the subframes and rocker panels, they come with a flexible wand.
Lastly buy some Eureka FLuid film and flood all your doors, hatch and nooks and crannies with that, it will run and drip out but keep the moisture and rust at bay.