Roof bars for surfboard

Hi, I have a Devon pop up roof and I'm after some roof bars high enough to put my surf board so it clears the roof (when it's down obviously ). Just wondered if anyone had any ideas of what to use?

 

Ive got van roof bars or have you tried velcro straps thru where bellows join roof brackets??

 

I've got a pair of these - as they're height adjustable, I think they can be adjusted so they're high enough to clear the poptop.