I'm in Canada, and have a '13 R/T Rallye.
I did not buy the trailer prep package. They informed me it is not an option on the Rallye's. It has everything it needs other than the hitch and wiring (as per my sales rep). They wanted $700 for the hitch and wiring. Took it across the street to a shop, they sold me a hitch, ball, shank, and wiring- installed, for $174.
I asked him if he had to have the lights activated or anything, he looked at me like I had three heads. Everything has worked flawlessly. Monday morning I am going to request a build sheet- see if it has an oil cooler.