When I purchased my Class C many years back, one of my early upgrade plans was to purchase and install (or have installed) hydraulic levelers. However, my first plan was to take some time using the RV for a while and after the first few weeks I determined that the RV doesn't move as much in the wind or with people walking as my previous trailer based RV's did.
In any case, I purchased a pair of these and I have used them at the rear bumper where the frame mounts are and they do help stabilize the RV during high winds, but they are not a lot of help otherwise. I think I have only used these two or three times. They are very easy to use, just not that I need them on mine most of the time.
My suggestion is to try out your RV for a while and see if you need further stabilization before you decide. Hydraulic levelers would be nice for unlevel parking areas, however I have got pretty good at using leveling ramps and generally only need a minute or two to place the ramps and drive up on them. Knowing how much leveling and ramp position for the leveling takes a few times at first to get good at and to be able to level the RV quickly, but with some time, using the the ramps for leveling is not a difficult or time consuming task for me to do anymore. ~CA