SkiZo
This is how I deal with barn doors and a tarp attached to roof rack.
Modified from another members design,can't remember who.Windguy maybe??
Standard conduit fittings.For wider tarp ,I have 2 pieces of foam pipe insulation with a slit that slide on to the top of the door.
I'm thinking a couple spring loaded adjustable shower rods to sit between the doors and hook a bungie net to those ... no mods required on the van at all.