I put my coach in D, set the cruise on 60 and let the engine compression help slow me on downgrades. Until you get into the mountains, the "hilly" are nothing the MH can't handle. I would almost not call then hilly.
On steeper downgrades (in the mountains only) I might use the Jake brake, the steeper, the higher position I go (mine has 3 positions, low, med, and high)
For the remainder of the state, don't sweat it. I have lived here all my life, driven MHs and 18 wheelers around the state. These "hilly" areas are nothing! If you stick to the interstates or 4 lanes, it's even easier driving around these parts.
FMCA #F431170, GS #822128658, Escapees SKP #112655
2012 Airstream Mercedes Interstate Class B