Lets see, most RV's now have flat screen LCD or LED HD TVs, and watching SD on them sucks.
I have DirecTV HD with the Slimeline SWM dish. It is easier to align than the old SD dish, as the mount has scales built in for shew and elevation. So one sets the mast vertical with a level, does the first two settings to the mount and then simply swings the azimuth while watching the signal meter on one of the TV's.
With SWM you only need one coax to the dish and have 8 receiver channels available. With two HDDVR's and a HDRec I am using 5 of the SWM's 8 channels. I also have whole home DVR running on my own ethernet router. Works great for a snowbirder.
DirecTV will do two address switches per year without a question. If you travel a lot I hear that Dish will switch locations more freely.
Chris