Domes work with Dish Network, Your son may have run into antennas that were setup for DirecTV and need to be reprogrammed. That's something that Dish isn't likely to have their guys do. RV techs should be able to do it.
With Dish, the recent dome antennas will aim at three satellites (110, 119 and 129) after running "check switch". They reposition the antenna based on the selected channel. They receive one satellite at a time. Domes will get HD with Dish, but not DirecTV. For sites with trees, you can carry a portable (either tripod or automatic) and leave it in storage when you have a clear view.