Do you want it just for the TT? If so, you will need a satellite dish. If you can afford it, I would get a carryout easy to use portable dish. http://www.campingworld.com/shopping/item/gm-2000-carryout-g2-automatic-portable-satellite-antenna-white/76528
If you don't want to spend that much on a satellite, get a dish with tripod. http://www.installeroasis.com/directv-satellite-dish-tripod-kit-for-rv-tailgating/?gclid=CPLnx9C-jr8CFUcV7Aodz1QAUw
Once you get the dish, call Directv and order a basic receiver and the package you want based on programming. They are clearly listed on their website www.directv.com and you can compare plans. Tell them it's for an RV and you do not need installation. (they won't install in an RV anyhow).
It's a bit tricky to learn to aim the satellite dish with tripod. The rest of the install is easy.