I have not run a 1431, but all of the ones I have ran including bar mowers, the manual states to run it on "float", that means to lock your control on the tractor in the float position, that allows the mower to float and not have any hydraulic pressure on it. The wear plates ride on the ground and most of the time they will slide over the top of most of the mounds, just flattening them out. Of course the higher ones will be cut the knives.
As for height control, when I am cutting Pearl Millet or Hay grazer, which you want to leave a minimum of 5 inch stubble for regrowth, I use hydraulic cylinder blocks on the rams for the raise/lower. They just snap around the hydraulic ram. The ones I have cost $12 a set, takes two sets, one for each side.
Hope this was helpful.