Interstate 10 pretty much runs the Southern route all the way out and we took this in October because we were concerned about driving through the mountains with the possibility of snow. We started in Minnesota and Iowa had already received snow so we straight-lined down I-35. We did zip up to I-40 to do Oklahoma City, Amarillo and Albuquerque then dropped down I-25 to do Las Cruces and jumping back on I-10. Roads were very good and lots of good campgrounds close to the route. Scenery from Las Cruces to LA is not as good as I-40 but safer with winter weather.
I went through this experience with DTV last year and found it very painful. If you contact Direct TV and tell them you want a box for your MH to add to your existing account you will get passed to multiple people who will not have any cogent answers other than you need a separate account for your DTV MH. The easy way is to take an existing registered box on your account and move it to your MH but you won't get your local channels once you move out of your home zip code satellite spot beam. I'm not certain of the legality of this approach so caveat emptor. If you want to go full legit you can contact one of the Winegard installers and they can set you up with a box and a new DTV account - not certain how local channels are handled.