For light surface rust, I've been using a wire brush on the end of my drill, and then using Krylon rust converter.
Krylon: Products: Outdoor Spaces® Rust Converter
Once that's cured, paint it up again (usually undercoating type prayer paint).
I have one spot on the frame where it meets the transfer case brace, and did the same thing, but I will eventually take the brace off and do a better job on it.
My side step had so much rust on it, that the rust showed up further around where I sprayed the converter. So, if there is a lot of rust, I dont think the spraycan stuff will do. You will need the POR product. I intend to use that on my frame and transfer case brace. May cost more, but worth the effort.
I haven't had the jeep long enough to tell you if this stuff holds up over a couple of years. I would expect it to do a reasonable job, or I wouldn't have used it
Maybe someone else with a longer time of using this product can chime in.