Glad to know you walked away from this experience and that "Dad's" efforts are amusing!
Perhaps you should also take some time out and think why you ended up parking your motorcycle in the back of a works van?
Negligence springs to mind as well as inexperience.
I am not trying to take the moral highground here; but the bottom line is you screwed up. Yes you have walked away from the incident and can have a laugh about it now. But the reality is that you need to address the facts behind your riding into the back of somebody else's vehicle.
