I'm guessing the photo you saw was the one that was actually in the passenger seat of a Class A or B motor coach. There is a drop down table there as one more clever workspace in the rig.
Never ever would recommend it while moving, because the machine could kill you even with a slam on the brakes, let alone an accident.
If you are talking hand stitching, I've done it all in the car, still would if my eyes were better.
