I did this very thing. The decal on one side (which the PO had obviously had pointed toward the sun a lot) was peeling off. After contacting the manufacturer, I learned they only stock decals for three years. So, I removed the peeling decal, used the "shadow" as a guide for taping, and spray painted the new graphic. I am pleased with the result.
My graphics fade from a deep graphite metallic through silver metallic to a a bronze metallic on the end. I was a little nervous about trying to duplicate this effect, but it turned out great.
The only thing I would do differently is that I would put clear-coat over the color. I could still do that, but I don't really want to go through the masking process again! Good luck with whatever choice you make. Every RV is a work of art, and you are the only one who needs to be pleased with the result.