If you still have the bracket on the inside of the tailgate on the passenger side, It would be easy to mount. Mine is removed as others have stated, it was fugly. I used the OEM bracket and part of the factory wires that were in the tailgate, just adding the ring. I initially just twisted the wiring to make sure the light worked, as the ring is LED and they only pass current in one direction. Both wires on the ring were black, so I had a 50/50 chance of being right. I was wrong the first time, swapped the wires over and it worked just fine. I prefer it.
Some stated will not pass it through inspection since it is not original. Some state, if you are stopped, will ticket you because it is not a CHMSL (Center High Mounted Stop Light). I have seen some down here that aren't very bright, but mine is fairly good.
Georgia no longer has a vehicle inspection law (passed in the 80's and then repealed several years later), nor do state troopers enforce NHSTA regulations.