Adding a hitch is not hard, and takes maybe an hour if you taking your time from start to finish. I went with OEM on both the hitch and wiring when I did my 2014. Don't let taking the rear bumper off scare you into not doing OEM vs say a uHaul hitch. I did the whole install by myself, and found the bumper is not heavy, and found it was surprisingly easy to take off and back on.
If you do go with the OEM, you'll notice when you take out the factory metal bumper for the hitch, that the hitch is a lot heavier and thicker. I would think that would be better for the rear end if some idiot hit you from behind.
You also don't necessarily need the hitch cover that goes over everything when there isn't a trailer/bike rack attached. It does look nicer with one however, and will also keep rain/snow and other things from getting into that area and rusting it over time.
If you do plan to tow, as has been mentioned, your limited to 3500 LBS because it didn't come from the factory with the tow package. If your just using it for a bike rack you will be just fine, and you also won't need wiring at all. Personally, I would do it anyway as you may find down the road you may need to tow something. That too is pretty easy, and if you get OEM wiring it will come with instructions on where to plug everything in, or at least mine did.
Sent from my SM-G988U using Tapatalk