If you have an awning rail on the side (Vamoose, Reimo etc) there are kits to attach to that where they don't use the roof rail mounting holes on your van. They likely require you to drill and rivnut your roof though. If you did remount your roof rail over the standard fitting kit your roof rail would be higher than the other side, unless you lifted that on similar fittings. That would be possible but may look strange.
