Has anyone solved this, or know of long stand-off clips. I'm aware of the very expensive brass ones, e.g. Toolstation 92644 st 0.5 each.
My next thought is to abandon clips all together, and find some way of using kingspan to insulate a pipe duct. As my next project is my circulating hot water main, I need a very good insulation characteristic to make it viable, without cold-bridging to the joist/rafter.