I can see where you're coming from mate, see how you get on with the Hpi & take it from there.

When you come to sell the car I'm sure you'll have taken the private plate off & have the original plate put back on so I would think that the Hpi report would only mention the plate change but not anything about the actual plate being recorded as it has nothing to do with the Porsche anymore so you should be ok but I stand to be corrected.