If you are already paying for DirecTV, why add Dish when you can simply take your DirecTV receivers from the house when you travel?
Using any satellite TV option you can call Dish or DirecTV and get the Network programming ABC, NBC, CBS, Fox local to where the RV is parked. You give them the zip code of your location and that's the Networks you receive. Sometimes there can be 2 different sets of Networks and if they are both close enough you can give an address in that market. Each market size varies dramatically from only a few hundred miles to well over 1000.