After several attempts, I've given up trying to make RLV from difficult terrain, since speed is often low and thus gives a strange experience as RLV.
Gravel and forest roads are more suitable and provide a better experience as RLV.
Here is my first attempt recorded on a foggy and rainy day.
DK_MTB_1 - test RLV recorded on gravel and forest roads in the area around Taulov, Denmark.