I have seen many, many, many ... did I say many! campers with a pick-up truck full of bicycles just piled on top of each other. I've often wondered how the foot pedals on one bicycle doesn't poke out the spokes on the one it's laying on. Watching poor old dad try to get them out of the truck bed, and then later when breaking camp, get them all back in is as good as going to the circus.
Edit: Clicky above:
Oh duh! I looked at the photo so quick, I didn't even realize ... it is PVC!
That's what I'd do.