Hello Paul,

As John says it is extra caster you require for the self centering on the steering. If you have already set the bump steer with the caster as it is set now then you could disconnect the swing bolt where it attaches to the TCA and wind it in say 3 full turns, the thread is a 2mm pitch & every 2 full turns will add approx 1 degree of caster so this would increase the caster to approx 6 degrees. This way after the test you can wind the swing bolt back to where you are now safe in the knowledge that you don't need to reset the bumpsteer. Quite often a new ball joint has a reasonable amount of stiction which can hinderthe self centering, once the ball joint loses its "newness" then things will free up, not helpful for IVA but something I have witnessed in the past which could be worth mentioning to the examiner on the retest.
If you have 1 degree of toe in then this could possibly affect the self centering too, 10minutes is a better starting point for the front axle.
With regards to the rear settings, the set up John has posted is very agressive on the rear (the front is fine), the rear toe is marginally more than I would start with & the rear camber is way more than I would look for on a road car.

Good luck with the retest!