Hi. If You choose to apply UV mapping in RC object You don't have many settings to play with.
Sometimes it is better to UV segment Yourself and leave that for RailClone to use. Such as in Your case. Note: I modified uvs of Your box as in general with Railclone - segments should be visualized laying in TOP viewport, not FRONT.
Also triplanar mapping can go to the rescue as well, such as in this
Hope this helps.