Hope not too late but, since you didn't get any responses....... We once owned a 2008 27RLSS. TT's have come a long way in the past 7 model years, with most now having satellite hook ups as wall as the basic cable and antenna connections.
Our 2008 had the cable connection located in the outside wall just outside of the "entertainment" area.
I found some pics of your model and if it has one, it should be right behind the slide. You should also check the inside wall connection plate. If it was the same as in 2008, it should have a 12v recepticle, coax connection and amplifier switch.
Pull the wall plate off and check behind it, how many cables? You may have to pull the radio out and/or the bottom panel to trace the coax as well. Be carefull, if its amplified, there will be 12v wires connected to the back of the wall plate.
Since you're this far, if you don't find anything other than the antenna coax and maybe the radio antenna connected to the wall plate, you might as well add your cable connector to the outside and be ready for spring.