Plain and simple, you need to invest big money if you want an automated system to acquire an HD Directv signal for RV use, need to decide if HD is worth it..
I've been setting up a Directv dish ever since the service went nationwide 2 decades ago, makes setting up our tripod HD Directv sat dish a breeze when we installed a couple of flatscreens in our rig several years ago.
Hopefully in the future there will be more economical automated choices for Directv in HD, but for now you have to drop major coin, go with a manual set-up, or forego HD altogether and settle for SD which is not an option for us.