Just wondered if anyone had fitted or used one of these (or other brands) on their van?

When we are on a trip i have four bikes on a fiamma rack hanging off the tailgate so i guess that one of these wouldnt add to the length - just sit underneath. It would also mean a lot of the cr@p i have to heave from one end of the van to the other could live outside - especially if it is wet or smelly
any experiences gratefully received.