Sandblasting/Pressure Washing Vinyl off FRP box

I own a box truck with some incredibly sunbaked vinyl covering the fiberglass box. I'm hoping that there might be a more efficient path to removing it. The paint underneath it is toast so I'm open to all methods that won't completely ruin the box.

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I've thought about sandblasting with walnut or pressure washing. Does anyone have any experience or thought on using more persuasive methods to remove vinyl from a FRP box?