I'm from NJ originally... and they salt the roads there just like PA... maybe a few less months, but same idea.
My last two CJ7s, I made rocker guards out of 4x4x1/4 inch angle iron. I painted them Rustoleum black... like 3 or 4 heavy coats. I then mounted them directly to the body with the entire surface that actually touched the body being RTV'd. Not just the edges, the whole dang thing where paint touched paint. One one, I masked and rustoleum'd the body too (the '80). I painted where the bolts went through. I siliconed the washers to the inside of the tub, after painting with Rustoleum.
I never found tapered head bolts that didn't rust... even the stainless ones. The '84 (the one with the tapered bolts) I RTV'd behind the head of the bolt too.
What I did was spooge RTV all over the rocker (after holes are drilled and rockers/Jeep well painted) and put it on without tightening the thing all the way. Basically tighten until RTV starts coming out, then stop. Wait for it to cure, then tighten all the way. This keeps from paint on paint contact.
On the bottom, because it was only 4 inches, it drained pretty well, and I made sure to power wash up between the rocker guard and the body. Also, the under side of the Jeep would get a fresh wire brushing and re-rustoleuming every spring.
I never pulled the rockers off the 84... but the guy I sold it too told me before he replaced the body that the rockers were just about the only non-rusted out section (some 4 years later). The 80, I pulled one off.... mainly cause I'm a glutton for punishment. Ok, I was going to boatside it... but once I got that one halfway off (cutting RTV the whole way) I was like "screw this". But it was too late. I had to take the thing all the way off.... saw no rust, cleaned RTV off, repainted and reinstalled... that was after about 2 years of use. And, the CJ's got winter duty more than the YJ did cause they were lincoln locked on 35's... where the YJ was open on 31s.
And, FWIW, Semi-Gloss black Rustoleum looks just like the powdercoating a lot of manufacturer's use on their stuff. You could mask the Jeep off and re-shoot the rockers with that at will. No need to remove them.
Just my 2 cents. I'm always leary about going to the frame, cause there is no way to make good and sure that the inside of the frame isn't rusting where you either bolted or welded the out riggers to the frame.