Can anybopdy make any (reasonably serious) suggestions other than to bin it and buy a proper bike rack?!)
I reasonably seriously doubt that using a rack not designed for your type of vehicle is a good idea at all.
Besides, even if you could get the rack to fit properly, in the time it takes to fit it, load up the bikes, and then unload them at the other end, you might as well have walked your bikes the half mile. Never mind the pollution implications of using your car for a half-mile journey.