Is there a way to have multiple rounds optimised with the furthest location first. So the van would drive to the furthest distance away and then work its way back to the starting point.
That is not supported as such.
A workaround may be to determine the furthest point yourself based on the location coordinates (formula) and set that as pickup point for all other locations using the restrictions. E.g.
when the index of the furthest location is 9.
That sounds like a good work around.