The couple were New Zealanders travelling home "further down the line", he said, unsure where.
Friend reminded motorists to pull over before attempting to check on any noises that may have come from their vehicle.
"I think the biggest thing is if you think there's anything wrong with your vehicle make sure you stop at the location before having a look at it or attempting to fix it."
The serious crash unit attended the scene but he didn't believe there was anything wrong with the vehicle.
Swerving skid marks were all that was left at the scene, at the exit to the Avantidrome, after the campervan was taken away.