That's nuts. One lose cable or something falling off the train and they would be turned to pudding. Not to mention the draft might pull them up or onto the track.
I've always thought about doing that But I've stuck to laying next to the moving train, where the railroad ties stick outside the rails....
It reminds me of an old Aerosmith video. Skip forward to 2:20 in the video. It's fake but still kinda cool. YouTube - Aerosmith - Livin' On The Edge