the lower quarter of my truck is looking a touch rough, just paint chips and slight rust bubbles. So I'm looking to sand down the rust and kill it before coating that lower quarter with something more durable- I'm going back and forth between bed liner and the stone guard spray but I'm hoping to keep the finish somewhat smooth. Has anyone had negative experiences with either product? what brand was it?

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2002 Ranger Edge
Ex-cab, step side
4.0L V6, 4x4