Looks like a great tow rig, NOT! He's gonna toast his transmission trying to tow with a Prius. Darn lucky he's going on a flat road too because I doubt his brakes or tranny could hold up to any kind of real decent or slowdown. God help the guy going of him if he had to do an emergency stop.
I wonder how hard the electric motors pull off a standing stop. and how much you could expect to get out of the regen braking before you touch the physical brakes/trans.