You need to do a search for this subject. This is a very hot topic, some say you can and some say the light weight trailers can not take the stress from the hitch. It also depends what you plan on doing with the hitch, bike rack or tow a boat?
We ditched the idea of a hitch on the back of the 2109s for a bike rack when we bought ours a year ago because of all the posts we read that the bumper won't support the weight. Several posts were from people who had experienced the bike rack (and bikes) falling off or of having the bumper become seriously twisted.
2109s - '14 Jeep Grand Cherokee diesel
You might want to call Rockwood & find out 1st. It is possible that the frame has changed but mine will not take anything else attached. I have not seen a 2015 but the 2014's had some nice upgrades from the 2013.
2013 Rockwood Mini Lite 2109S
2010 Toyota Tundra 4WD
i had a custom hitch made for an ultralite and was bolded to the frame with grade 8 bolts. I am looking to do the same with my new 1905 when it arrives. A dealer said welding voids, but bolting seems to be ok. Still doing research. The custom hitch does very well, I carry 4 bicycles on it.