Using proper break in procedures, engineer out the plastic chain tensioner, checking your fasteners at every stop, and regulating your speed to 20 mph. a cross country trip is not out of the question. However due to the lack of suspension and the engine vibration your body suffers a great deal. The "gator bite" in your hands, wrists, and arms can be severe, think carpal tunnel with bee stings. The hammering on the spine makes for an interesting night.
The moped ride is much more Cadillac like and is overengineered to take the abuse of higher speeds. I would really recommend one for an enjoyable trip versus a test of willpower and endurance.