When I saw the picture of the trailer, I thought it was being towed by a big rig. Offhand, I would think that a standard pickup could easily lose control of a trailer that long if the driver had to suddenly slow down or swerve to avoid the motorcycles, especially if that group was following the practice that I have seen of having outriders on the center line to make oncoming traffic hug the shoulder. An aquaintence of mine was killed doing this when an oncoming driver would not give way. He basically had to make a split second choice of how he was going to die.