There are several issues with DirecTV and RV'ing. 1) the only way to upgrade to a HD receiver is to have an HD satellite and the only one that supports HD on\in an RV is the Wineguard Traveler. IT is expensive, but the reality is you must have the equipment to support HD.
DirecTV does support RV's, I just upgraded my system to the Genie, but I have the Wineguard system, which will support the Genie. When I first called and ask if they support the RV, they said yes as long as the satellite supports HD, all I had to do was take my receivers from home and put them in the RV. I have moved the system from home to the RV, everything works fine.
I upgraded to the genie while on the road with no problem, called DirecTV and requested the upgrade to the Genie and told them that I was currently in my RV not at my Home base and I had the Wineguard which supports HD, they actual came to the RV and changed out the system and left, no problem.
The big issue with DirecTV is that you either have to have a permanently installed HD satellite, which defeats the purpose of RV'ing or dish out the funds for the Wineguard system.
As long as you have an HD satellite, you can take your DirecTV anywhere.