In reply to Greasy Prusiks:
I disagree.
All motor racing isn't a silly stunt to me, but certain aspects of motor sport are. Trying to jump across the Grand Canyon, Wall of Death riding, etc.
A lot of UKC ers could walk up the bottom half of the Slide, if top roped.
A fair few extreme off road vehicles could possibly make it to the half way line as well.
I don't know how viable the top half as far as the traverse would be to one of those extremely powerful specialist machines but I'm willing to bet that there are people willing to have a go. Few bolts across the top, arrest cable across the crux moves and a decent Unimog winch at the top for the lower.
For the safety conscious , use a fast winch and effectively top rope the whole stunt.
Access? Well, Lundy is famous for its use of landing craft so that would be even more filmogenic.....
Shit! Doing the bastard Clarkson's job for him already and not getting a penny for it!