It certainly requires you to master the correct technique. I didn't think I needed it when I bought the car. Now I use it regularly. Works great for me. I don't know if I'd drop over $800 on the parts to add it after the fact, though, if it can even be done. For that kind of money, you'd be better off buying the higher trim level at the time of purchase if you really wanted it.
I agree with the other posts above about asking the dealer. While a small number of dealers might be able to think outside the box like that, most would never sanction trying to add something that isn't meant to be an accessory. The dealer will probably say no. You'd have to do some homework yourself to figure out if the wiring connection is there to accept the sensor. Talk to the parts people instead of the service department, and you might find someone who can help look through some diagrams to explore the feasibility.
It may not be a safe assumption that the bumper already has whatever you need to attach the bracket. The lower bumper cover is different on Limited and Platinum because it's a different color. If you put on the OEM hitch, then you need different part numbers again for the replacement bumper cover (with the notch in it for the hitch) for Limited and Platinum, for the color and the relocated kick sensor attachment.