So, I got my truck, an 89 Bronco ][, and attached the rope to the truck hitch with some shackles, webbing and proof chain. I slowly pulled away, and the rope got tighter and tighter. I pulled until a friend was suspended in mid-air in the middle of the rope. Then, I simply put the car in park, and walked away. I tested the bridge in my harness while my buddy in crime Ian watched carefully. The rope was extremely tight when one of us was on it, and I later calculated the forces (I am a physics major, afterall).
Needless to say, the bridge worked perfectly, and Ian went across for the competition. Everybody thought it was pretty cool.