In terms of legal, what are you worried about: everyday driving, or getting into an accident and then having a lawsuit? Driving every day on the road, you are not going to get into any trouble. The DOT will go by tire ratings as a rule of thumb and occasionally they will check GAWRs. In the case of a lawsuit you are on your own.

Yes, a truck/body shop can re-rate your truck but most will not do it for liability reasons.