You can drill the rivets out, and the other sides will simply fall on the floor, or possibly on top of the frame back there...not a real issue. I'm not sure if there is a backing plate on the other side of the rear wall for that bracket, tho...you may need to look and see, just in case. If there is, you'll need to be sure and re-install it when ya put it all back together.
The light itself should have a power and ground on the connector, so no external ground is needed.
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Joel Adams
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