I never understood rolling for distance moved when troops were drilled into marching at a certain speed. Always seemed wrong to me. Then I tried walking quickly across what seemed at first sight a flat field. The subtle undulations made going at a constant rate very tricky.
I would be inclined to use a variable movement rate to model the effects. And perhaps strips of mat or cloth for the peaks or troughs and the remaining underneath mat as the corresponding troughs or peaks…
