Ok, my brain had been busy with this while I’ve been asleep.
I jack one side up, undo the ARB clamp bolts on that side, drop the van down, jack other side up and undo the clamp bolts , drop van down and then fold ARB down out of the way.
I should then be able to jack one side at a time up and drop the hub low enough to free the spring. Sound like a plan? Working today but I think I might be able to finish early enough to have a go tonight
One other thought, is the front ARB going to cause me a similar problem if I want to wind them down a bit?