Going up is easy, the art is in coming down. As mentioned. Use the gears to hold back the RV. On the interstates 2nd gear coming down may be all you need. However, on the really steep, and twisty mountain roads where the speed limit is usually 25, or 35 MPH. You will need to use 1st gear. And you will need to put it in first before you start down. DO not let it get away from you, keep it slow from the start. It is much easier to keep control, than it is to lose it, and try to get it back.
So go slow, and enjoy. Your gas engine will IF you use the gears, will save you from ever heating up the brakes