I've just ordered one of Andy's seatbelts http://www.extremekites.com.au/forums/viewtopic.php?f=18&t=16228&view=unread#unread
But to tide me over until it arrives I did a little inventing yesterday and cobbled this together out of a velcro strap with snap lock hook that I found at Bunnings for $7.95 and an old chicken loop I had lying around.
it'll be finished on the weekend.