My Class C is older so it only has a 4 speed trans but that doesn't change much. What I do is anticipate the hill and tap the brake pedal to kick off cruise control than I push the button to shift it out of 4th gear to 3rd and as it gets down to around 40 I back off the accelerator and manually shift down into 2nd. This eases the abruptness of the down shift and I have better control over RPMs. However reving doesn't harm the engine up to 4500 to 5000 rpm's(wish mine had a tach) and that's what it does to make power.