I've had both bumpers off. Easy peasy.
Download the manual, from the wiki. Good info, in there.
Be prepared, with a place to set it down, like a moving blanket, or saw horses. Don't use those cheap folding tubular stands. They will collapse, at the most inopportune moment.
Also, what does the harness connect to? Side markers? Should be able to put the car, up on ramps and get after it, from underneath.
Sent from my SM-G955U using Tapatalk