Whether it is Directv or Dish network, we simply purchased the very same satellite dish we had mounted on our roof at home either on Ebay or some other online retailer. That way we are assured of receiving the exact same programming we have at home. I paid just over $50 for the HD sat dish we are currently utilizing for satellite tv while RVing.
With either service provider, if you have an account for your home, a separate account is not needed. With Directv we simply brought our HD receiver from our master bedroom. With Dish Network we just purchased the VIP receivers for our rig since they are under $100, eliminating the hassle of bringing receivers back and forth from RV to home.
For HD satellite tv, both Directv and Dish network require acquisition of 3 satellites, while SD channels can be viewed with the acquisition of a single satellite. Either configuration is easy to attain as long as mast is plumb to start the process. I highly suggest to practice setting up at home to avoid frustrations at the campground.
One of the concerns is that many RVs are not really set up for satellite tv. My rig actually had a label above the single exterior coax input claiming satellite ready. Much to my dismay, the satellite signal could not reach my sat receiver due to a splitter where my interior coax output was located. There is a quick mod that alleviates this issue.
For us, the actual pointing of the sat dish is the easiest part, it takes longer to unwind the coax and set-up the tripod. Once again, to assure quick acquisition of the satellites in the southern sky, sat dish mast must be plumb, particularly for HD content, purchasing a tripod that has levels built in greatly simplifies the process.