I was recently able to source a pair of gently used R65 side panels off eBay. Original Bronco Brown paint with white and red R65 logos. Not the most attractive color combination I’ve seen but the plastic panels and the mounting lugs were solid.
Before removing the stick-on vinyl logos, I made a pencil rubbing to save the original positioning of the stickers; just in case I ever want or find a fresh pair... but most definitely in a different color.
With a bucket of warm water, some 320 Wet-or-Dry, a Soft Block-brand rubber sanding block and an hour or so, the side panels were smoothed. I was able to remove much of the Bronco Brown paint without getting into the plastic substrate. A few minor paint nicks also disappeared with the 320.
By the way, it was real work using a wooden craft stick to dress down the original paint between the five louvered slots. Both the original primer and color were sorta fuzzy. Left as is, the finished rehab would have been even worse.
After washing the panels, a couple coats of primer was sprayed on and left to cure for a few days. 400 grit was used to sand down the primer - that’s including the louver spaces.
A medium-full coat of gloss black was then sprayed onto the panels. To insure full paint cure, five days cure time elapsed before color sanding with 400 and 600 grit. This sanding leveled the paint and eliminated a few specs that drifted onto the first color coat. More sanding between the louvers, too.
Final color was shot and, again, allowed to cure for a few days. Color sanding began with 600 grit and progressed through 1200 grit. A brisk rub with Meguiar's #1 Cleaner was followed by the Meguiar's #2 Polish, some Meguiar's Carnuba Wax and we’re sparkling good to go.

A pencil rubbing will go into the shop manual and will provide accurate placement should I decide to go with some R65 stickers on the side panels.

The original Bronco Brown paint needed quite a bit of 320 grit work to get rid of a few nicks and scratches.

Two coats of primer and some 400 grit got the panels ready for color... Gloss Black. All sanding was done with Wet-or-Dry paper used really wet. Keep the sanding slurry rinsed off your work, primer and most definitely the color.

The first color coat was sprayed on as a medium heavy coat. After five days for full cure, another pass with the 400 grit leveled the paint. Two days later, two additional coats of color were laid down.

After a couple days for paint cure, the final color was sanded with 600 grit through 1200. The Meguiar's polish and wax system brought out the depth of the color and a high gloss.
All primer and paint was done with Ace Hardware rattle cans and their "Premier" line of paints. $3.49 per can. Gunning the panels with my small detail gun would have required five gun set-ups and five clean ups. Too much hassle for such a small job.
Monte "I'm tired of sanding" Miller