Just installed a Rugged Ridge hitch about 20 mins ago on My 2012 JKU.
6 bolts come out. Look under each end of the Rear bumper you will see a brace holding the bumper to the Jeep. remove the 16mm bolts holding the bumper to the brace. Then look at the back of the rear bumper next to the body mount, you will see a bracket bolted to the rear cross member with another bolt above it holding the bracket to the bumper. Remove the top bolt only! you can loosen the one holding the brace to the cross member but there is no need to remove it. Pulling it out will result in the bracket falling off and hitting you in the face (don't ask how I know this). That's it, open the tailgate and the bumper will fall off.
If you have an air ratchet it makes the job a ton faster but all bolts can be reached easily enough