Just do it the same way I did. Get a SWM slimline dish (best to get the 5 LNB model if you get one of the less expensive meters), a power supply and a heavy duty tripod with 2" pole. This uses only one wire from the dish to your DVR and you get to use both tuners. Since I don't have a TV visible from the outside I also purchased a meter and a DirecTV ASL1 to do the aiming. It takes a couple of setups to get the hang of things, but after that it is not difficult. There is a slight advantage to a stand-alone dish since you can get it away from obstructions.
Just a word of caution. If your RV is more than about 5 years old, it most likely has RG-59 versus RG-6. D* recommends RG-6 for SWM technology so you may have to replace your coax.
Obviously, if you love camping in areas with a lot of trees you may have problems. But, it works great in most parks.
