Proper RV braking on a downgrade
I agree with this:
"The use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine.
Once the vehicle is in the proper low gear, the following is a proper braking technique:
(1) Apply the brakes just hard enough to feel a definite slowdown. (2) When your speed has been reduced to approximately five mph below your "safe" speed, release the brakes. This brake application should last for about three seconds. (3) When your speed has increased to your "safe" speed, repeat steps 1 and 2". From California DMV.