I realise that Roadrunners know a lot more about organising it than I do, but I feel that you could organise it more easily with a lot more reliance on runners to find their way and to be more self-reliant crossing roads - long relay races operate on the same principle, after all.
There was really only one short stretch of road (near Gatwick) where the traffic was heavy and uncomfortably close, but I can see it's hard to get round that, short of building a new cycle path to run on. Much of the rest was pavement or very quiet road.
I'm also intrigued to know if you could organise it in parallel with the L2B bike ride.
Glad I did it at least once, but I really was hoping to try it again. Ah well. Maybe if the cyclepaths get better it can be resurrected.